Device and system characterized by measurement, report, and change procedure by terminal for changing transmission/reception point, and base station procedure for supporting same

ABSTRACT

The disclosure relates to a communication technique for convergence of an IoT technology and a 5G communication system for supporting a higher data transmission rate beyond a 4G system, and a system therefor. The disclosure can be applied to an intelligent service (for example, a smart home, a smart building, a smart city, a smart cart or connected car, health care, digital education, retail business, security and safety-related service, etc.) on the basis of a 5G communication technology and an IoT-related technology. The disclosure defines a mobility method for a terminal residing in a system in which transmission/reception points (TPRs), supporting solely some protocols among entire access stratum protocols comprising PHY, MAC, RLC, PDCP, and RRC, coexist in a wireless communication system. Specifically, the disclosure defines a method for dynamically changing, depending on determination by a base station, a beam and a transmission/reception point to be used for transmitting information to or receiving information from a terminal through a method in which a system using multiple beams notifies, in advance, of a measurement reference signal transmitted using transmission/reception points of different networks, to allow a terminal to select a required reception beam from a corresponding resource and measure beam information of each transmission/reception point, or a terminal transmits measured information as feedback in which each transmission/reception point is specified. Accordingly, the disclosure can provide a criterion of rapid and highly precise determination for changing a beam and a transmission/reception point and thus prevent a terminal from needlessly measuring and reporting, so as to achieve an effect of reduction in the power consumption of the terminal and reduction of delay in change of a transmission/reception point.

TECHNICAL FIELD

The disclosure relates to a next-generation wireless communicationsystem. More specifically, the disclosure relates to a measurement,report, and change procedure of a terminal for a system including one ormore transmission and reception points, a method of transmitting ameasurement reference signal for each transmission and reception pointand a method of collecting reports by a base station for themeasurement, report, and change procedure, and a method, procedure andsystem for changing a transmission and reception point of each terminal.

BACKGROUND ART

In order to satisfy a wireless data traffic demand that tends toincreases after the 4G communication system commercialization, effortsto develop an improved 5G communication system or pre-5G communicationsystem is being made. For this reason, the 5G communication system orpre-5G communication system is called a beyond 4G network communicationsystem or a post LTE system. In order to achieve a high data transferrate, the 5G communication system is considered to be implemented in anmmWave band (e.g., 60 GHz band). In order to reduce a loss of electricwaves and increase the transfer distance of electric waves in the mmWaveband, beamforming, massive MIMO, full dimensional MIMO (FD-MIMO), arrayantenna, analog beamforming and large scale antenna technologies arebeing discussed in the 5G communication system. Furthermore, in order toimprove the network of a system, technologies, such as an improved smallcell, an advanced small cell, a cloud radio access network (cloud RAN),an ultra-dense network, device to device communication (D2D), wirelessbackhaul, a moving network, cooperative communication, coordinatedmulti-points (CoMP) and reception interference cancellation, are beingdeveloped in the 5G communication system. In addition, hybrid FSK andQAM modulation (FQAM) and sliding window superposition coding (SWSC)that are advanced coding modulation (ACM) schemes, improved filter bankmulti-carrier (FBMC), non-orthogonal multiple access (NOMA) and sparsecode multiple access (SCMA) are being developed in the 5G system.

Meanwhile, the Internet evolves from a human-centered connection networkover which human generates and consumes information to Internet ofThings (IoT) in which information is exchanged and process betweendistributed elements, such as things. An Internet of Everything (IoE)technology in which a big data processing technology through aconnection with a cloud server is combined with the IoT technology isemerging. In order to implement the IoT, technical elements, such as thesensing technology, wired/wireless communication and networkinfrastructure, service interface technology and security technology,are required. Accordingly, technologies, such as a sensor network,machine to machine (M2M) and machine type communication (MTC) for aconnection between things, are recently researched. In the IoTenvironment, an intelligent Internet technology (IT) service in which anew value is created for human life by collecting and analyzing datagenerated from connected things may be provided. The IoT may be appliedto fields, such as a smart home, a smart building, a smart city, a smartcar or a connected car, a smart grid, health care, smart homeappliances, and advanced medical services, through convergence andcomposition between the existing information technology (IT) and variousindustries.

Accordingly, various attempts to apply the 5G communication system tothe IoT are being made. For example, 5G communication technologies, suchas a sensor network, machine to machine (M2M) and machine typecommunication (MTC), are implemented by schemes, such as beamforming,MIMO, and an array antenna. The application of a cloud wireless accessnetwork (cloud RAN) as the aforementioned big data processing technologymay be said to be an example of convergence between the 5G technologyand the IoT technology.

With the advent of smartphones, the amount of user data increasesgeometrically. The need for such data usage is further increasing. Thismeans that a high bandwidth is necessary. To this end, a high frequencyneeds to be used. However, as a high frequency is used, a signalattenuation degree for each distance rises. That is, if a centerfrequency of 30 GHz or more is used, a coverage reduction of a basestation attributable to signal attenuation is inevitable. Furthermore,there are problems in that many beams need to be used due to thecoverage reduction and latency attributable to the use of many beams isincreased.

In a wireless communication system, a structure is taken intoconsideration in which one base station including multiple transmissionand reception points capable of transmission and reception supports awide physical area in order to improve latency attributable to afrequent exchange of terminal information and for efficient resourceutilization. Such a system has been researched in various ways in aconventional technology and has been implemented.

Representatively, the following systems may be taken as the existingtechnologies:

A distributed antenna system (DAS) in which different transmission andreception points under one base station are simply implemented asphysical antennas and transmit or receive the same signal,

A remote radio head (RRH) system in which different transmission andreception points under one base station are implemented as a structureincluding an antenna and a simple RF stage and can transmit or receivedifferent signals,

Furthermore, a coordinated multi-point transmission/reception (CoMP)system in which different transmission and reception points under one ordifferent base stations transmit and receive the same information to andfrom one user at the same time through synchronization or the othertransmission and reception point is silent while one transmission andreception point transmits and receives information.

In such a background, a measurement, report and change method of aterminal and an operation method of a base station supporting the same,for a transmission and reception point change are necessary.

Technical Problem

An embodiment of the disclosure proposes a method for a terminal tomeasure a reference signal for the selection of a beam and transmissionand reception point, a method for the terminal to feed measuredinformation back, and a method for the terminal to changing a beam andtransmission and reception point in an environment in which transmissionand reception points having different protocol structures are present inthe same base station maintaining an RRC connected state with theterminal, and proposes a method for the base station to allocate aterminal-unique beam and transmission and reception point referencesignal resource, a method for the base station to share allocatedresource information with the terminal, a resource allocation andsignaling method for receiving measured information through feedback,and a method for the base station to change a beam and transmission andreception point in a system configured with the base station and thetransmission and reception points for the methods.

Furthermore, synchronization signals transmitted at a transmission pointbeing used by a terminal as one reception beam and a transmission pointnot being used by the terminal as one reception beam cannot be receivedat the same time in a beamforming environment. In an embodiment of thedisclosure, in order to solve the problem, there may be a method for aterminal to measure an adjacent transmission and reception pointtransmission reference signal while turning a dumb reception beam. Insuch a method, however, time is taken long, and a transmission andreception point maximum measurement time is very long, that is, the“number of transmission and reception points×the number of beams withintransmission and reception point×the number of terminal beams.” There isproposed a method of efficiently measuring a transmission referencesignal corresponding to only the “number of transmission and receptionpoints×the number of beams within a transmission and reception point”using an effective terminal reception beam at the reference signaltransmission times of different transmission and reception points basedon information transmitted by a base station.

Solution to Problem

In accordance with an embodiment of the disclosure, an operation methodof a terminal may provide a method, including receiving resourceconfiguration information, including reference signal configurationinformation of a first transmission and reception point (TRP) andreference signal configuration information of a second TRP, from thefirst TRP; measuring a reference signal corresponding to the first TRPand a reference signal corresponding to the second TRP based on theresource configuration information; reporting the measurementinformation on the reference signal corresponding to the first TRP andthe reference signal corresponding to the second TRP to the first TRP;receiving TRP change indication information from the first TRP; andchanging a configuration for the second TRP based on the TRP changeindication information.

In accordance with an embodiment of the disclosure, a terminal mayprovide a terminal, including a transceiver configured to transmit andreceive signals and a controller configured to control to receiveresource configuration information, including reference signalconfiguration information of a first transmission and reception point(TRP) and reference signal configuration information of a second TRP,from the first TRP, to measure a reference signal corresponding to thefirst TRP and a reference signal corresponding to the second TRP basedon the resource configuration information, report the measurementinformation on the reference signal corresponding to the first TRP andthe reference signal corresponding to the second TRP to the first TRP,to receive TRP change indication information from the first TRP, and tochange a configuration for the second TRP based on the TRP changeindication information.

In accordance with an embodiment of the disclosure, an operation methodof a base station may provide a method, including transmitting resourceconfiguration information, including reference signal configurationinformation of a first transmission and reception point (TRP) andreference signal configuration information of a second TRP, to aterminal through the first TRP; transmitting a reference signalcorresponding to the first TRP and a reference signal corresponding tothe second TRP based on the resource configuration information;receiving measurement information on the reference signal correspondingto the first TRP and the reference signal corresponding to the secondTRP from the terminal; determining a TRP change for the terminal basedon the measurement information; transmitting TRP change indicationinformation to the terminal through the first TRP; and changing aconfiguration of the second TRP for the terminal in accordance with theTRP change indication information.

Advantageous Effects

In accordance with an embodiment of the disclosure, there can beprovided a measurement, report, and change procedure of a terminal for asystem including one or more transmission and reception points, a methodfor a base station to transmit a measurement reference signal and amethod for a base station to collect reports for each transmission andreception point for the measurement, report, and change procedure, and amethod, procedure and system for changing a transmission and receptionpoint of each terminal.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram showing a TRP protocol structure according to anembodiment of the disclosure.

FIG. 2 is a diagram showing an environment including a multi-TRP and amulti-beam according to an embodiment of the disclosure.

FIG. 3 is a diagram showing a method of measuring a multi-TRP beam in amulti-beam, multi-TRP environment according to an embodiment of thedisclosure.

FIG. 4 is a diagram showing a terminal initial access procedure in amulti-beam, multi-TRP environment according to an embodiment of thedisclosure.

FIG. 5 is a diagram showing a terminal initial access procedure in amulti-beam, multi-TRP environment according to another embodiment of thedisclosure.

FIG. 6 is a diagram showing a TRP change method according to anembodiment of the disclosure.

FIG. 7 is a diagram showing a TRP change method of a base stationthrough the RS measurement of a terminal according to an embodiment ofthe disclosure.

FIG. 8 is a diagram showing a beam RS set change method of a basestation through the RS measurement of a terminal in an embodiment of thedisclosure.

FIG. 9 is a diagram showing a TRP change method when a base stationcontrols the mobility of a terminal in an embodiment of the disclosure.

FIG. 10 is a diagram showing a procedure of changing a TRP after a grantin an embodiment of the disclosure.

FIG. 11 is a diagram showing a procedure of changing a TRP after a grantin another embodiment of the disclosure.

FIG. 12 is a diagram showing a procedure of changing a TRP based on anRRC message in another embodiment of the disclosure.

FIG. 13 is a diagram showing a method of exchanging terminal informationbetween a TRP and a base station according to an embodiment of thedisclosure.

FIG. 14 is a diagram showing a method of exchanging terminal informationbetween a TRP and a base station according to another embodiment of thedisclosure.

FIG. 15 is a diagram showing a method of sharing terminal informationwhen a TRP change is requested in an embodiment of the disclosure.

FIG. 16 is a diagram showing a method of sharing terminal informationwhen a TRP change is requested in another embodiment of the disclosure.

FIG. 17 is a diagram showing a method of sharing terminal informationwhen a TRP change is requested in another embodiment of the disclosure.

FIG. 18 is a diagram showing a terminal feedback trigger and TRP changemethod according to an event in an embodiment of the disclosure.

FIG. 19 is a diagram showing a terminal feedback trigger and TRP changemethod according to an event in another embodiment of the disclosure.

FIG. 20 is a diagram showing a terminal according to an embodiment ofthe disclosure.

FIG. 21 is a diagram showing a base station according to an embodimentof the disclosure.

MODE FOR THE INVENTION

Hereinafter, preferred embodiments of the disclosure are described indetail with reference to the accompanying drawings. It is to be notedthat the same reference numbers are used throughout the drawings torefer to the same elements. Furthermore, a detailed description of knownfunctions or constructions that may make the gist of the disclosurevague is omitted.

In this specification, in describing the embodiments, a description ofcontents that are well known in the art to which the disclosure pertainsand not directly related to the disclosure is omitted in order to makethe gist of the disclosure clearer.

For the same reason, in the accompanying drawings, some elements areenlarged, omitted, or depicted schematically. Furthermore, the size ofeach element does not accurately reflect its real size. In the drawings,the same or similar elements are assigned the same reference numerals.

The merits and characteristics of the disclosure and a method forachieving the merits and characteristics will become more apparent fromthe embodiments described in detail in conjunction with the accompanyingdrawings. However, the disclosure is not limited to the disclosedembodiments, but may be implemented in various different ways. Theembodiments are provided to only complete the disclosure of thedisclosure and to allow those skilled in the art to understand thecategory of the disclosure. The disclosure is defined by the category ofthe claims. The same reference numerals will be used to refer to thesame or similar elements throughout the drawings.

In the disclosure, it will be understood that each block of theflowchart illustrations and combinations of the blocks in the flowchartillustrations can be executed by computer program instructions. Thesecomputer program instructions may be mounted on the processor of ageneral purpose computer, a special purpose computer, or otherprogrammable data processing apparatus, so that the instructionsexecuted by the processor of the computer or other programmable dataprocessing apparatus create means for executing the functions specifiedin the flowchart block(s). These computer program instructions may alsobe stored in computer-usable or computer-readable memory that can directa computer or other programmable data processing equipment to functionin a particular manner, such that the instructions stored in thecomputer-usable or computer-readable memory produce an article ofmanufacture including instruction means that implement the functionspecified in the flowchart block(s). The computer program instructionsmay also be loaded on a computer or other programmable data processingapparatus to cause a series of operational steps to be performed on thecomputer or other programmable apparatus to produce a computer-executedprocess, so that the instructions performing the computer or otherprogrammable apparatus provide steps for executing the functionsdescribed in the flowchart block(s).

Furthermore, each block of the flowchart illustrations may represent aportion of a module, a segment, or code, which includes one or moreexecutable instructions for implementing a specified logicalfunction(s). It should also be noted that in some alternativeimplementations, the functions noted in the blocks may occur out oforder. For example, two blocks shown in succession may in fact beexecuted substantially concurrently, or the blocks may sometimes beexecuted in the reverse order, depending upon the functionalityinvolved.

In this case, the term “unit”, as used in the embodiment means softwareor a hardware component, such as a field programmable gate array (FPGA)or an application-specific integrated circuit (ASIC), and the “unit”performs specific tasks. The “unit” may advantageously be configured toreside on an addressable storage medium and configured to operate on oneor more processors. Accordingly, the “unit” may include, for example,components, such as software components, object-oriented softwarecomponents, class components, and task components, processes, functions,attributes, procedures, sub-routines, segments of program code, drivers,firmware, microcode, circuitry, data, databases, data structures,tables, arrays, and variables. The functionalities provided in thecomponents and “units” may be combined into fewer components and “units”or may be further separated into additional components and “units.”Furthermore, the components and “units” may be implemented to operate onone or more CPUs within a device or a security multimedia card.

In an embodiment of the disclosure, a base station (BS) is a main agentcommunicating with a terminal, and may be referred to as a “BS, basetransceiver station (BTS), nodeB (NB), eNodB (eNB), gNB, an access point(AP), etc. In an embodiment of the disclosure, the term called a basestation or eNB is chiefly used, but is not limited thereto. The basestation may be used as a gNB of a 5G NR system.

A terminal is a main agent communicating with a base station, and may bereferred to as a “user equipment (UE), device, mobile station (MS),mobile equipment (ME), a terminal, etc.

In an embodiment of the disclosure, a transmission and reception pointmay refer to a transmission and reception point (TRP).

FIG. 1 is a diagram showing a TRP protocol structure according to anembodiment of the disclosure.

Referring to FIG. 1, a distributed unit structure configured withmultiple transmission and reception points taken into consideration inan embodiment of the disclosure takes various candidates intoconsideration, and may include a centralized unit and a distributedunit. The centralized unit and the distributed unit may include an RFstage, a physical layer (L1 or PHY), and a higher layer (MAC stage, RLCstage, PDCP stage, and RRC stage). For example, referring to acombination of a CU and a DU1, the RRC, PDCP, RLC, MAC, and L1 layer arepresent in the CU, and only the RF stage is included in the DU. Acombination of the CU and a DU6 is a case where the RRC, PDCP layer arepresent in the CU and the RLC, MAC, L1 layer and RF stage are present inthe DU6. In an embodiment of the disclosure, various protocol stacks ofvarious CUs and DUs illustrated in FIG. 1 may be applied.

In an embodiment of the disclosure, a base station may be a conceptincluding a CU and at least one DU. Furthermore, the base station may bea concept, including a CU, at least one DU, and at least one TRP. TheTRP may correspond to the antenna of the base station. A different TRPmay correspond to a different antenna of the base station. The TRP maycorrespond to at least one of the resource set, NR-SS resource set, beamset, or antenna configuration set of a channel stateinformation-reference signal (CSI-RS). For example, if TRPs aredifferent, CSI-RS resource sets, NR-SS resource sets, beam sets, andantenna configuration sets may be different. A TRP may manage aplurality of beams, and a plurality of beams managed by one TRP may bedefined as a beam set. What a UE transmits a signal to a TRP may beconstrued as being what the UE transmits a signal to a base stationconnected to the TRP. What a UE receives a signal from a TRP may beconstrued as being what the UE receives a signal from a base stationconnected to the TRP. If a base station is construed as including a TRP,the transmission and/or reception of a signal, information, messagebetween the base station and a TRP may be understood as being aninternal operation of the base station.

FIG. 2 is a diagram showing an environment including a multi-TRP and amulti-beam according to an embodiment of the disclosure. Referring toFIG. 2, the environment including a multi-beam may include an eNB #1, aneNB #2, and a terminal. The eNB #1 may include a plurality of TRPs TRP#1 to the TRP #k. The eNB #2 may include a plurality of TRPs TRP #1 tothe TRP #k. Each TRP may operate a plurality of beams. For example, eachTRP may operate a beam #1 to a beam #n. The n value may be differentdepending on the TRP.

In FIG. 2, it is assumed that the terminal moves while being served bythe Beam #1 of the TRP #1 of the eNB #1. As the eNB #1 moves, the beamof the TRP #1 for the terminal may be changed. When the terminal is outof coverage of the TRP #1 while moving by changing the serving beam ofthe TRP #1, a TRP change to another TRP (e.g., TRP #K) may occur. Whenthe terminal moves from the TRP #K, a beam change may occur. When theterminal is out of coverage of the eNB #1, a serving eNB may be changedto the eNB #2. Likewise, when the terminal moves from the serving eNB#2, a beam change and a TRP change may occur.

A transmission and reception point taken into consideration in anembodiment of the disclosure may be a structure present at a locationphysically separated from any CU and another transmission and receptionpoint having one of the protocol structures of FIG. 1. A terminal mayperform wireless communication based on the same terminal ID (e.g.,C-RNTI) as the CU using such different multiple transmission andreception points.

In this case, the corresponding terminal may communicate with thetransmission and reception points or the CU using any ID (e.g., Cell ID)owned by a base station including all the multiple transmission andreception points or may communicate with the TRPs and the CU using atransmission and reception point ID (e.g., TRP ID) that is uniquelyallocated and shared with the terminal or may communicate with the TRPsor the CU to which a corresponding protocol belongs using an ID (e.g.,MAC ID, RLC ID, TCP ID, IP, . . . ) included in a protocol within eachtransmission and reception point.

In an embodiment of the disclosure, the following various methods aredescribed in order to support a system in which multiple TRPs aremanaged. Each of the methods may be independently performed and a methodof combining a plurality of methods may be performed.

-   -   A method for a system to explicitly (additionally) transmit a        unique TRP ID different from a Cell ID to a terminal    -   A method for a system to share an implicit rule by which        terminals can distinguish between TRPs    -   A method for a base station within a system to transmit a        measurement reference signals using multiple TRPs    -   A method for a terminal to receive the measured reference        signals of multiple TRPs    -   A method for a terminal to feed measurement information from        multiple TRPs back to a base station to which the terminal        belongs    -   A method for a base station and terminal within a system to        change a TRP

<Method of Explicitly Transmitting Unique TRP ID to UE>

1. a method of transmitting a TRP ID through a synchronization signal

A. a method of adding an additional TRP-SS—new synchronization signalfor each TRP

: the existing synchronization signal (PSS, SSS, for Cell ID)+a newsynchronization signal (new SS for a TRP ID)

a-1. Can identify a TRP as a new synchronization signal

a-2. Define a TRP ID as a new SS having a sequence identifier andtransmit it. Reference is made to the following contents for a method ofdefining a new SS.

-   -   New SS definition

A sequence d(0), . . . , d(K) used by a UE to obtain an extendedsynchronization signal is a length-K Zadoff-chu (ZC) sequence and isdefined as follows.

${{d(n)} = e^{{- {jM}}{\prod\frac{n{({n + 1})}}{K}}}},$

n=0, 1, . . . , K−1

In this case, K is a maximum value of the sequence, and a TRP (or CSI-RSresource set, NR-SS resource set, beam set) number (e.g., 63) and M(e.g., 23) within each base station are root indices.

A sequence used to obtain an extended synchronization signal that may beobtained within an OFDM symbol l is defined as a d(n)cyclic shift and isas follows:

In this case, when l=0, . . . , 2·N_(symb) ^(DL)−1, a cyclic shift valueis defined in Table 1-A.

TABLE 1-A Cyclic shifts for the extended synchronization signal I Cyclicshift Δ_(t) 0 0 1 7 9 14 3 18 4 21 5 25 6 32 7 34 8 38 9 41 10 45 11 59. . . . . . K/4 K-2

A sequence used to scramble an extended synchronization signal in ai∈{0, 25} subframe is defined as follows:

${r_{1{(n)}} = {{\frac{1}{\sqrt{2}}( {1 - {2 \cdot {c( {2n} )}}} )} + {j\frac{1}{\sqrt{2}}( {1 - {2 \cdot ( {{2n} + 1} )}} )}}},{n = 0},1,{{\ldots\mspace{14mu} K} - 1}$

In this case, the pseudo-random sequence c(m) is defined as follows:

The pseudo-random sequence is defined as a length-31 Gold sequence. Whenn=0, 1, . . . , K−1, an output sequence c(n), that is, a length M_(PN),is defined as follows:

c(n)=(x ₁(n+N _(c))+x ₂(n+N _(c)))mod 2

x ₁(n+(K−1)/2)=x ₁(n+3)+x ₁(n))mod 2

x ₁(n+(K−1)/2)=x ₂(n+3)+x ₂(n=1)+x ₂(n))mod 2

In this case, Nc=1600, and the first m-sequence is initialized usingx₁(0)=1, x₁(n)=0, n=1, 2, . . . , ((K−1)/2−1). The second m-sequence isinitialized as c_(init)=Σ_(l=0) ^((K−1)/2−1)x₂(i)·2^(i). In this case,the parameter value is determined depending on use of the sequence.

In the i-th subframe, a pseudo-random sequence generator needs to beinitialized using c_(init)=2¹⁰·(i+1)·(2·N_(ID) ^(TRP)+1)=2·N_(ID)^(TRP)+1.

A sequence d^(l)(n) used in the extended synchronization signal isdefined as follows.

d ^(l)(n)=r ₁(n)·d ^(l)(n), n=0, . . . ,K−1

B. New SS only—method of transmitting only an SS for synchronization foreach TRP without SS including the existing Cell ID

: SSs for a TRP ID only

C. Modified PSS/SSS—method of modifying the existing SS and including aTRP ID

: Method of transmitting a TRP ID in a PSS and SSS, that is, theexisting synchronization signals in addition to a cell ID (PSS/SSS carryboth Cell ID and the TRP ID)

c-1. Embodiment: A PSS is the same as that of LTE, and a scheme formodifying an SSS as follows.

n_(ID) ⁽²⁾∈{0, 1, 2} is a physical layer identifier (ID) and may be usedin a cell and TRP (or CSI-RS resource set, NR-SS resource set, beamset). A sequence d(0), . . . , d(61) used for a second synchronizationsignal has a form of interleaved concatenation produced using twolength-31 binary sequences. The concatenated sequence is a scrambledsequence given by the first synchronization signal. The secondsynchronization signal may be transmitted through the following port.p=300, . . . , 313.

The second synchronization signal defined as a combination of the twolength-31 sequences may be differently defined as follows for eachsubframe:

${d( {2n} )} = \{ {{\begin{matrix}{{s_{0}^{(m_{0})}(n)}{c_{0}(n)}} & {{in}\mspace{14mu}{subframe}\mspace{14mu} 0} \\{{s_{1}^{(m_{1})}(n)}{c_{0}(n)}} & {{in}\mspace{14mu}{subframe}\mspace{14mu} 25}\end{matrix}{d( {{2n} + 1} )}} = \{ \begin{matrix}{{s_{1}^{(m_{1})}(n)}{c_{1}(n)}{z_{1}^{(m_{0})}(n)}} & {{in}\mspace{14mu}{subframe}\mspace{14mu} 0} \\{{s_{0}^{(m_{0})}(n)}{c_{1}(n)}{z_{1}^{(m_{1})}(n)}} & {{in}\mspace{14mu}{subframe}\mspace{14mu} 25}\end{matrix} } $

In this case, 0≤n≤30. S^(m) ⁰ and S^(m) ¹ denote a physical layer cellID group N_(ID) ^(Cell(1)) and a physical layer TRP (or CSI-RS resourceset, NR-SS resource set, beam set) ID group N_(ID) ^(TRP(1)),respectively.

2. Method of inclusion and transmission in reference signal

A. Method of using a unique sequence for a TRP (unique sequences forTRPs)

a-1. Method of allocating a unique sequence for each TRP

Method 1) divide and use the existing Cell ID space

A reference signal sequence η(m) is defined as follows:

${{\eta(m)} = {{\frac{1}{\sqrt{2}}( {1 - {2 \cdot {c( {2m} )}}} )} + {j\frac{1}{\sqrt{2}}( {1 - {2 \cdot ( {{2m} + 1} )}} )}}},$

m=0, 1, . . . , 8·(N_(RB) ^(maxDL)−18)−1

In this case, l=0, 1, . . . , 13 is an OFDM symbol number. Thepseudo-random sequence c(i) is defined above, and the pseudo-randomgenerator may be initialized using the following.

1) c _(init)=2¹⁰·(7·(n ₂+1)+l′+1)·(2·N _(ID) ^(cell) ·N _(ID)^(TRP)+1)+2·N _(ID) ^(cell) ·N _(ID) ^(TRP)+1

2) c _(init)=2¹⁰·(7·(n ₂+1)+l′+1)·(2·N _(ID) ^(cell)·2·N _(ID)^(TRP)+1)+2·N _(ID) ^(cell)·2·N _(ID) ^(TRP)+1

3) c _(init)=2¹⁰·(7·(n ₂+1)+l′+1)·(2·K+1)+2·K+1,

N _(ID) ^(cell)=(K)mod(N _(ID) ^(cellmax)/2), N _(ID) ^(TRP)=(└K/(N_(ID) ^(cellmax)/2)┘+N _(ID) ^(cell)+1)mod(N _(ID) ^(cellmax)/2)

4) Or when

$n_{s} = \lfloor \frac{l}{7} \rfloor$

and l′=l mod 7, any type of unique initialization code produced usingdifferent distinguishable N_(ID) ^(cell) and N_(ID) ^(TRP) at the earlystage of an OFDM symbol

Method 2) New sequence design—unique sequence design for each cell, eachTRP including a N_(ID) ^(cell) and N_(ID) ^(TRP)

B. Method of using a different resource for each TRP (differentresources for TRPs)

b-1. Allocated a different frequency (carrier, subcarrier, channel, abandwidth, etc.) to a different TRP

b-2. Allocate a different time (slot, symbol, subframe, radio frame) toa different TRP

b-3. Allocate a radio resource (radio resource block), represented as adifferent frequency and time, to a different TRP

C. Different resources & sequences for TRPs

c-1. Method of mixing different frequency/time/sequences anddistinguishing between TRPs

3. Method of inclusion and transmission in broadcasting information

Share information for distinguishing between TRPs using broadcastinformation, such as a master information block (MIB), a broadcastchannel (BCH), a system information block (SIB) 1 or 2 (BCH), adedicated SIB.

<Method of Sharing an Implicit TRP Classification Method with a UE>

A base station may deliver a method by which a UE can distinguishbetween TRPs to the UE.

1. Table in which a Beam ID and a TRP ID are mapped Beam ID TRP ID 0 1 12 . . . . . . N K

2. Method of calculating a TRP ID as a Beam ID

A. MSB K bits of Beam ID=TRP ID

B. (Beam ID)mod(K)=TRP ID

C. Floor(Beam ID/K)=TRP ID

D. ceiling(Beam ID/K)=TRP ID

E. Indication that the order of Beam RS transmission=TRP ID

3. Method of classification based on an RS resource ID

A. Provide a UE with an associative relation between a sync signalresource ID, a CSI-RS resource ID and a TRP in a table/rule form

B. Provide a UE with an associative relation between a sync signal beamID, a CSI-RS beam ID and a TRP in a table/rule form

4. Method of classification based on an RS resource set

A. A UE considers configured/scheduled RS resource sets as a differentmeasurement subject and measure/change it.

B. A network may manage TRPs by differently allocating RS resource setsfor each TRP.

C. A CSI-RS resource set, an NR-SS synch burst/burst set may be used.

The information may be provided to a UE in the following form.

1. Method of inclusion and transmission in broadcast information May betransmitted using an MIB (BCH), an SIB 1 or 2 (BCH), and/or a DedicatedSIB.

2. Inclusion and transmission in dedicated (unicast) information

New MAC-CE use transmission, may be included in an RRC message (RRCConnection reconfiguration, RRC Connection Setup) as a new IE andtransmitted, and may be transmitted as a PHY message and/or may betransmitted as a MAC message.

If the implicit TRP classification method is used, a base stationincludes a rule using the implicit classification method, instead ofincluding a TRP ID, when it transmits resource configuration informationof different TRPs or configures a resource based on an already set rule.This may be applied to step 713 of FIG. 7A.

Furthermore, a UE may use a rule using the implicit classificationmethod, included in a corresponding message when it distinguishesbetween different TRPs within received resource configurationinformation, or may distinguish between resources allocated by differentTRPs based on an already set rule. This may be applied to step 716 ofFIG. 7A.

<Method for a Base Station to Transmit a TRP-Measured Reference Signal(RS)>

[Mobility Using an RS Transmitted by Base Station Allocation at a UEUnique Period/Time]

1. A TRP (or TRP-higher eNB) determines that each TRP transmits RSs fordifferent Tx beams at the same time/frequency resource, and may notify aUE of corresponding scheduling information.

A. A known method uses a new IE within a PDCCH unicast, PDCCH sweepingbroadcast/multicast, RRC connection reconfigure,

B. An RS may be determined as follows based on received feedback/reportinformation with respect to one or multiple UEs

b-1. In the case of one UE target, allocation is performed in order ofthe best beam of beams reported to have reception performance (RSRP,RSRQ, CQI, SNR, SINR, RSSI) of a given threshold or more, which may bereceived by the corresponding UE

b.2. Transmit information to a higher eNB through front haul withrespect to an adjacent TRP transmission beam or directly transmit theinformation to a corresponding TRP through an interface (X2, S1, . . ..)

b.3. Or determine to select given beams

b.4 Or Allocate adjacent beams (from the nearest beams) of the best beamfor each TRP.

C. When a UE performs reception using each known TRP measurement value,the UE selects a better UE beam and measures a scheduling resource usingthe corresponding beam.

2. A TRP (or TRP-higher eNB) may determine that each TRP transmits an RSfor a different TRP at a different time (or frequency) resource andnotify a UE of corresponding scheduling information.

<Method for a UE to Measure a TRP>

FIG. 3 is a diagram showing a method of measuring a multi-TRP beam in amulti-beam, multi-TRP environment according to an embodiment of thedisclosure.

Referring to FIG. 3, a system may include a UE 300, a TRP 1 301, a TRP 2302 and a base station 305. The UE 300 is a UE belonging to the basestation 305, and exchanges information with the base station using theTRP1 301. In the embodiment of FIG. 3, different beams of different TRPscan be observed precisely and fast through two steps, such as a commonbeam measurement procedure and a UE dedicated beam measurementprocedure.

A common beam measurement procedure 320 is to receive a common referencesignal transmitted by TRPs, to search for a coarse (available) TRP beamand a UE beam pair, and to feed the measurement results of the commonreference signal back. For example, the common reference signal may usea synchronization signal. The UE may perform the common beam measurementprocedure using the synchronization signal.

A task of searching for the best beam using only the common referencesignal requires a very long time in a system in which the number ofbeams is many (measurement corresponding to a maximum “number oftransmission and reception points×the number of beams within atransmission and reception point×the number of UE beams” is necessary).Accordingly, a coarse beam direction is selected using the commonreference signal, and UE-specific unique beam measurement is performedon fine beams adjacent to a selected beam using the coarse beamdirection.

In this case, for the selection of a TRP to be transmitted by the basestation and beam selection for each TRP, the UE need to feed back thatit is better for different TRPs to transmit which beams and the bestbeam (or Best N beams) for each TRP (or best K TRP).

At operation 311, the TRP 1 301 transmits information for common beammeasurement to the UE. The information may be at least one of broadcastinformation, multicast information, or unicast system information. Theinformation for the common beam measurement may include at least one ofrandom access channel (RACH) subframe information, reception beaminformation in an RACN subframe, a system frame number (SFN), a physicalhybrid-ARQ indicator channel (PHICH), a bandwidth, an antenna port,system information scheduling information, information on a cell ID, aTRP ID, or a beam ID.

At operation 312, the TRP 2 302 may transmit information for common beammeasurement to the UE 300. For information included in the informationfor common beam measurement, reference is made to the contents describedat operation 311.

At operation 313, the UE measures a common beam reference signal for theTRP 1 301. At operation 314, the UE measures a common beam referencesignal for the TRP 2 302. The UE 300 may measure the common referencesignals while sweeping reception beams.

At operation 315, the UE 300 may update the common beam measurementresults. The UE 300 may update the common beam measurement results foreach TRP. The UE 300 performs RS measurement on different TRPs, andupdates measurement information for filtering purposes, for example, ifnecessary.

At operation 317, the TRP 1 301 may indicate that the common beammeasurement results should be reported. To report the best beam or Nbeams having good performance for each TRP may be indicated. Common beammeasurement result report information may indicate that information on aTRP ID, a beam ID, beam quality should be reported.

At operation 318, the UE 300 may report the common beam measurementresults. The UE 300 may report the common beam measurement results tothe TRP 1 301. The common beam measurement results may be delivered tothe CU of the base station 305.

In UE dedicated beam measurement 340, the base station 305 selects atransmission beam for each TRP, which will be transmitted to the UE 300,using the feedback information. In this case, in general, UE beamscapable of receiving beams transmitted by different TRPs may bedifferent for each TRP (because TRP locations are different).Accordingly, if the UE 300 can receive a reference signal using only onebeam at once, the UE may measure only a TRP present in one direction andonly a beam belonging to the corresponding TRP at a given time.

Accordingly, the base station 305 needs to transmit corresponding TRPinformation (e.g., ID, TRP sequence) regarding when each TRP transmitsinformation, while transmitting UE dedicated beam measurementtransmission signal scheduling information so that the UE can receivereference signals transmitted by different TRPs using a given beam at agiven time. In the UE dedicated beam measurement procedure, a UEdedicated beam may be used. The UE dedicated beam may use a CSI-RS, forexample.

At operation 341 and operation 342, the base station 305 selectstransmission beams for each TRP using information, such as feedbackinformation (e.g., common beam measurement results) of the UE.Furthermore, the base station 305 may schedule the reference signal ofeach TRP for UE dedicated beam measurement. The reference signalscheduling information for each TRP may be delivered to each TRP. Thebase station 305 may provide the TRP 1 301 with reference signalinformation for the TRP 2 302 in addition to reference signalinformation for the TRP 1 301. In this case, the reference signal may bethe UE dedicated reference signal of each TRP.

At operation 343, the TRP 1 301 may provide the UE 300 with informationon a TRP dedicated reference signal. The information on a TRP dedicatedreference signal may include beam information, resource informationrelated to a TRP ID. In addition to dedicated reference signalinformation of the TRP1 301, dedicated reference signal information ofthe TRP2 302 may be provided to the UE 300.

At operation 344, the TRP 1 301 transmits a dedicated reference signal.At operation 345, the TRP 2 302 transmits the dedicated referencesignal. The UE 300 measures the dedicated reference signal transmittedby each TRP while sweeping reception beams.

At operation 346, the UE 300 updates the measurement results of thededicated reference signal for each TRP.

At operation 347, the TRP1 301 transmits, to the UE 300, informationindicating that the measurement results of the dedicated referencesignal should be reported.

At operation 348, the UE 300 reports the measurement results of thededicated reference signal for each TRP.

FIG. 4 is a diagram showing a terminal initial access procedure in amulti-beam, multi-TRP environment according to an embodiment of thedisclosure. FIG. 4 is a diagram showing an initial access procedure whenTRPs can be distinguished.

Referring to FIG. 4, a system may include a UE 400, a TRP 1 401, a TRP 2402 and a base station 405. The UE 400 is a UE belonging to the basestation 405, and exchanges information with the base station using theTRP1 401.

At operation 411 and operation 413, the TRPs 401 and 401 may transmitinformation for initial access. The information may be at least one ofbroadcast, multicast, or unicast system information. The information mayinclude at least one of random access channel (RACH) subframeinformation, reception beam information in an RACN subframe, a systemframe number (SFN), a physical hybrid-ARQ indicator channel (PHICH), abandwidth, an antenna port, system information scheduling information,information on a cell ID, a TRP ID, or a beam ID.

At operation 413, the UE 400 measures a beam reference signal for theTRP 1 401. At operation 414, the UE 400 measures a beam reference signalfor the TRP 2 402. The reference signal may be a common referencesignal. The UE 400 may measure a reference signal or common referencesignal while sweeping reception beams.

At operation 415, the UE 400 may update beam measurement results. The UE400 may update the measurement results of the common reference signal.The UE 400 may update common beam measurement results for each TRP. TheUE 400 performs RS measurement on different TRPs, and updatesmeasurement information for filtering purposes, for example, ifnecessary.

At operation 417, the UE may select a proper TRP for initial accessbased on the beam measurement result. For example, the UE may select aTRP having the best beam measurement results. In the embodiment, it isassumed that the TRP 1 401 has been selected. In the embodiment of FIG.4, it is assumed that in the initial access results, the UE 400 maydistinguish between TRPs based on beam measurement or common beammeasurement. Accordingly, the UE 400 may distinguish between TRPs andselect a proper TRP.

At operation 418, the UE 400 transmits a radio resource control (RRC)connection request message to the TRP 1 401. The UE 400 may transmit theRRC connection request message through a beam selected with respect tothe selected TRP.

At operation 419, the TRP 1 401 may deliver an RRC connection requestmessage to the base station 405. At operation 420, the base station 405may transmit an RRC connection setup message to the TRP 1 401. The UE400 may transmit the RRC connection request message using an RACHresource for the selected TRP or the selected beam. At operation 421,the TRP 1 401 may transmit the RRC connection setup message to the UE400. The TRP1 401 may transmit the RRC connection setup message to theUE 400 using a dedicated resource.

FIG. 5 is a diagram showing a terminal initial access procedure in amulti-beam, multi-TRP environment according to another embodiment of thedisclosure. FIG. 5 is a diagram showing an initial access procedure ifTRPs cannot be distinguished.

Referring to FIG. 5, a system may include a UE 500, a TRP 1 501, a TRP 2502 and a base station 505. The UE 500 is a UE belonging to the basestation 505, and exchanges information with the base station using theTRP1 501.

At operation 511 and operation 513, the TRPs 501 and 501 may transmitinformation for initial access. The information may include at least oneof broadcast, multicast, or unicast system information. The informationmay include at least one of random access channel (RACH) subframeinformation, reception beam information in an RACN subframe, a systemframe number (SFN), a physical hybrid-ARQ indicator channel (PHICH), abandwidth, an antenna port, system information scheduling information,information on a cell ID, a TRP ID, or a beam ID.

At operation 513, the UE 500 measures a beam reference signal for theTRP 1 501. At operation 514, the UE 500 measures a beam reference signalfor the TRP 2 502. The reference signal may be a common referencesignal. The UE 500 may measure a reference signal or common referencesignal while sweeping reception beams.

At operation 517, the UE may select a proper beam for initial accessbased on the beam measurement results. For example, the UE may select abeam having the best beam measurement results. In the embodiment of FIG.5, it is assumed that in initial access results, the UE 500 cannotdistinguish between TRPs based on beam measurement or common beammeasurement.

At operation 518, the UE 400 transmits a radio resource control (RRC)connection request message to the TRP 1 501. The UE 500 may transmit theRRC connection request message using an RACH resource for the selectedbeam. The UE 500 may transmit the RRC connection request message throughthe selected beam. The UE 500 may transmit information on the selectedbeam along with the RRC connection request message.

At operation 519, the TRP 1 501 may deliver the RRC connection requestmessage to the base station 505. At operation 520, the base station 505may transmit an RRC connection setup message to the TRP 1 401. Atoperation 521, the TRP 1 501 may transmit the RRC connection setupmessage to the UE 500. The TRP1 501 may transmit the RRC connectionsetup message to the UE 500 using a dedicated resource.

<Method for a Base Station and UE to Change a TRP>

1. TRP change method using L1 beam feedback

A. Transparent method

i. UE beam quality measurement

ii. UE beam ID, beam quality report

iii. Distinguish between beams associated with base station-reported TRP

iv. A base station transmits beam change command to a UE

v. The UE changes a beam (at a designated time/frame after a lapse of anagreed time/frame)

vi. The base station changes a beam+a TRP (at a designated time/frameafter a lapse of an agreed time/frame)

B. Method using an explicit TRP ID

i. Measure beam quality for each UE TRP

ii. A UE reports a TRP ID, a beam ID, beam quality

iii. A base station determines a beam/TRP change based on the reportedbeam and TRP

iv. The base station transmits a TRP change command to the UE

1. TRP ID only

2. TRP ID+beam ID

v. The UE changes a TRP

1. Change a TRP and use the best beam that has been implicitlypreviously reported

2. Use a TRP and beam ID as commanded

vi. The base station changes a beam+TRP

2. A beam/TRP change using MAC beam feedback

A. Change based on RACH msg 3 reception beam feedback

i. The base station transmits a TRP change command (msg 4 or a differentPDCCH or mac msg) to the UE

1. TRP ID only

2. TRP ID+beam ID

ii. The UE changes a TRP

1. Change a TRP and use the best beam that has been implicitlypreviously reported

2. Use a TRP and beam ID as commanded

3. At a designated time/frame after a lapse of an agreed time/frame

iii. The base station changes a beam/TRP (at a designated time/frameafter a lapse of an agreed time/frame)

B. Change based on MAC CE reception

i. The base station transmits a TRP change command (msg 4 or a differentPDCCH or mac msg) to the UE

1. TRP ID only

2. TRP ID+beam ID

ii. The UE changes a TRP

1. Change a TRP and use the best beam that has been implicitlypreviously reported

2. Use a TRP and beam ID as commanded

3. At a designated time/frame after a lapse of an agreed time/frame

iii. The base station changes a beam/TRP (at a designated time/frameafter a lapse of an agreed time/frame)

3. Method of changing a TRP feedback/change method based on an RRCconfiguration according to a base station/network configuration

A. If base station/network configurations are different, a TRPfeedback/change method is fixed by transmitting an RRC message providingnotification that the base station/network configurations are different

B. Define an RRC IE capable of transmitting the following 0˜3 Config 2bits

C. Or define an RRC IE that transmits L1/MAC signaling and change=0, RRCsignaling and chang=1

i. If it is 1, feed back and change only a beam

ii. If it is 1, perform measurement for each TRP, MR report, and changeafter receiving a base station RRC message

4. A TRP change using RRC control msg

A. The UE transmits measurement report based on a measurement triggerevent for each TRP

B. MR triggering events

i. T1: measured quality of a TRP is higher than a threshold

ii. T2: measured quality of a TRP is lower than a threshold

iii. T3: measured quality of a neighbor TRP is offset higher than themeasured quality of the serving the TRP

iv. . . .

C. A new RRC-connection reconfiguration IE for MR

i. TRP ID, TRP measurement, measurement ID,

An MR reception base station determines whether to change a TRP changeand transmits it as an RRC message

FIG. 6 is a diagram showing a TRP change method according to anembodiment of the disclosure.

Referring to FIG. 6, a system may include a UE 600, a TRP 1 601, a TRP 2602 and a base station 605.

Referring to FIG. 6, the UE 600 is a UE belonging to the base station605 and exchanges information with the base station using the TRP1 601.The UE 600 may have explicitly recognized that it uses the TRP1 601using the ID of the TRP1 601 or may not explicitly recognize that ituses the TRP1 601, and may have recognized that it also performscommunication with the base station using any beams belonging to theTRP1 701, for example, a CSI-RS resource set, an NR-SS resource set, aTRP antenna Tx/Rx configuration or any beam set.

At operation 611 and operation 612, the base station 605 selects RSs tobe transmitted by the TRP1 601 and the TRP2 602 the resources of thecorresponding RSs so that the UE 600 can perform measurement, anddelivers such information to the TRP1 601 and the TRP2 602 if theinformation needs to be provided to the TRPs. In this case, the TRP1 601needs to schedule RS information of the TRP2 602 in addition to the RSof the TRP1 601 with respect to the UE 600. Accordingly, the basestation 605 may provide the TRP1 601 with both RS configurationinformation of the TRP1 601 and configuration information of the TRP2602.

At operation 613, the TRP1 601 provides the UE 600 with the configuredresource configuration information of the TRP1 601 and TRP2 602 so thatthe UE 600 can measure each of the TRPs. In this case, a direct TRP IDassociated with resource configuration information of a different TRPmay be provided or any resource segmentation method of enabling the UEto indirectly distinguish between the TRPs, for example, a method oftransmitting the RSs of different TRPs at time intervals may be used sothat the UE 600 can recognize that the corresponding RSs are transmittedby different TRPs.

At operation 614, the TRP1 601 transmits an RS to the UE 600, asallocated, for measurement. At operation 615, the TRP2 602 transmits theRS to the UE 600, as allocated, for measurement.

At operation 616, the UE 600 performs RS measurement on different TRPs,and updates measurement information for filtering purposes, for example,if necessary.

At operation 617, the TRP 1 601 may indicate that beam measurementresults should be reported. The TRP 1 601 may indicate that the bestbeam or N beams having good performance should be reported for each TRP.The beam measurement result report information may indicate thatinformation on a TRP ID, beam ID, beam quality should be reported.

At operation 618, the UE 600 may report beam measurement results. The UE600 may report the beam measurement results to the TRP 1 601.

At operation 619, the TRP1 601 may determine whether a TRP change isrequired. The TRP1 601 may determine whether a TRP change is requiredbased on the reported measurement results. The determination method maybe the same as a measurement report transmission event. For example,when the measurement results of the reference signal of the TRP2 aregreater than the measurement results of the reference signal of the TRP1by a value of a preset offset, the TRP1 601 may determine that a TRPchange is required.

At operation 620, if it is determined that a TRP change is not required,the process proceeds to operation 621. If it is determined that a TRPchange is required, the process proceeds to operation 622.

At operation 621, the TRP1 601 does not need to provide the UE 600 withany information related to a TRP change. However, even in such a case,the UE 600 may need to change a beam being used within the same TRP. Insuch a case, the TRP1 601 may enable the UE 600 to perform a beamchange.

At operation 622, the TRP1 601 transmits information for requesting(e.g., TRP change indication information) a TRP change operation to theUE 600. At operation 622, the TRP1 601 transmits information forrequesting a TRP change operation to the UE 600. The TRP changeindication information (TRP change indication message) may be a physicallayer message (PHY downlink control information), may be a MAC CEmessage, and may be an IE included in an RRE message, for example, anRRC connection reconfiguration message. For a detailed example that maybe included in the corresponding TRP change signal, reference is made tothe embodiment of FIG. 7.

At operation 623, the TRP1 601 provides a TRP change request and UEinformation to the base station 605. A procedure of notifying the basestation 605 of information indicating that a TRP change is necessary isnecessary because the TRP1 601 has determined a TRP change. Theinformation may include at least one of a UE ID, a UE bestbeam/CSI-RS/NR-SS ID, the best beam/CSI-RS/NR-SS ID measured by a UE anda measured value of the TRP 2, MAC information, RLC information, or TRP2timing advance measurement information of the UE, etc.

At operation 624, the base station 605 may provide the TRP2 602 with aTRP change request and UE information. The TRP2 602 may prepare thejoining of the UE based on the TRP change request and UE information.

At operation 625, the UE 600 prepares to receive information of a targetTRP, the TRP 2 included in the corresponding TRP change request messageover a fixed time after the TRP change request message is received oruntil a scheduled resource is received. The UE 600 changes a receptionconfiguration so that the reception beam of the UE 600 is suitable forthe reception of the downlink resource of the TRP2 included in the TRPchange request message and a beam/CSI-RS/NR-SS having a beam association(QCL) relation with the corresponding resource.

At operation 626, the TRP1 601 flushes information on the UE 600.

At operation 627, the TRP2 602 prepares to transmit a signal, includedin the TRP change request message, to the UE over the fixed time afterthe TRP change request message is received.

FIG. 7 is a diagram showing a TRP change method of a base stationthrough the RS measurement of a terminal according to an embodiment ofthe disclosure.

Referring to FIG. 7, a system may include a UE 700, a TRP 1 701, a TRP 2702 and a base station 705.

The UE 700 is a UE 700 belonging to the base station 705 and exchangesinformation with the base station using the TRP1 701. The UE 700 mayhave explicitly recognized that it uses the TRP1 701 using the ID of theTRP1 701 or may not explicitly recognized that it uses the TRP1 701, andmay have recognized that it performs communication with the base stationusing any beams belonging to the TRP1 701, for example, a CSI-RSresource set, an NR-SS resource set, a TRP antenna Tx/Rx configurationor any beam set.

At operation 711 and operation 712, the base station 705 selects RSs tobe transmitted by the TRP1 701 and the TRP2 702 and the resources of thecorresponding RSs so that the UE 700 can perform measurement, anddelivers such information to the TRP1 701 and the TRP2 702 if theinformation needs to be provided to the TRPs. In this case, the TRP1 701needs to schedule RS information of the TRP2 702 in addition to the RSof the TRP1 701 with respect to the UE 700. Accordingly, the basestation 705 may provide the TRP1 701 with both RS configurationinformation of the TRP1 701 and RS configuration information of the TRP2702.

At operation 713, the TRP1 701 provides the configured resourceconfiguration information of the TRP1 701 and TRP2 702 to the UE 700 sothat the UE 700 can measure each of the TRPs. The resource configurationinformation may include RS configuration information of the TRP1 701 andRS configuration information of the TRP2 702. In this case, a direct TRPID associated with resource configuration information of a different TRPmay be provided or any resource segmentation method of enabling the UEto indirectly distinguish between the TRPs, for example, a method oftransmitting the RSs of different TRPs at time intervals may be used sothat the UE 700 can recognize that the corresponding RSs are transmittedby different TRPs.

At operation 714, the TRP1 transmits an RS to the UE 700, as allocated,for measurement. At operation 715, the TRP2 702 transmits the RS to theUE 700, as allocated, for measurement.

At operation 716, the UE 700 performs RS measurement on different TRPs,and updates measurement information for filtering purposes, for example,if necessary.

At operation 717, a network may configure RRM measurement bytransmitting an RRC connection reconfiguration message for the TRPmeasurement and report of the UE, and may configure measurement reporttransmission. At operation 717, the base station 705 may transmit theRRC connection reconfiguration message to the TRP1 701. At operation718, the TRP1 701 may deliver the RRC connection reconfiguration messageto the UE 700. The message of operation 717 and operation 718 may haveincluded the RS scheduling message of operation 713 or the measurementevent configuration of operation 717 and operation 717 may have beenincluded in the RS scheduling message of operation 713. A measurementreport transmission event of the UE that may be taken into considerationmay be the A1˜A6 events of the LTE standard or may be the C1, C2 eventsor may be the following events of a form modified from the existing C1,C2 events.

-   -   Event C1′: when a CSI-RS resource set (or TRP or NR-SS resource        set or beam set or antenna configuration set) is greater than a        set absolute threshold;    -   Event C2′: when a CSI-RS resource set (or TRP or NR-SS resource        set or beam set or antenna configuration set) is better than a        reference CSI-RS resource set (or TRP or NR-SS resource set or        beam set or antenna configuration set) by a set offset or more    -   Event C1′ (when a CSI-RS resource set is greater than a set        absolute threshold;

The UE confirms:

1> whether the following specified condition C1-1′ is satisfied bytaking into consideration the following specified condition C1-1′ as theentry condition of an event;

1> Whether the following specified condition C1-2′ is satisfied bytaking into consideration the following specified condition C1-2′ as theescape condition of an event;

Inequality C1-1′ (entry condition)

Mcr+Ocr−Hys>Thresh

Inequality C1-2′ (escape condition)

Mcr+Ocr+Hys<Thresh

The variables of the equation are defined as follows:

Mcr is a measured value of a CSI-RS resource set in which any offset isnot taken into consideration.

NOTE: In this case, Mcr may be derived through a measured value of oneor one or more CSI-RS resources included in the CSI-RS resource set, andmay have included multiple CSI-RS measurement values. The UE may deriveone Mcr using the multiple CSI-RS measurement values.

An example of methods that may be used to derive Mcr is as follows:

-   -   After filtering, the best N CSI-RS measurement values are        averaged in order of measured values    -   After filtering, measured values included in any condition among        the best N CSI-RS measurement values, for example, within a        counterpart value offset in an absolute value or more or the        best measurement value are averaged in order of the measured        values    -   After filtering, the best N CSI-RS measurement values are added        in order of measured values    -   After filtering, measured values included in any condition among        the best N CSI-RS measurement values, for example, within a        counterpart value offset in an absolute value or more or the        best measurement value are added in order of the measured        values.

※ Filtering may be performed in various layers, for example, L1 or L2 orL3. A method, such as weight averaging by applying an arithmeticaverage, a geometric average or weight set by a network to measuredvalue ordering, may be used as a method for averaging.

Ocr is a CSI-RS resource set unique offset. Hys is a hysteresisparameter for a corresponding event, and Thresh is a threshold for thecorresponding event.

Mcr, Thresh is represented in dBm.

Ocr, Hys is represented in dB.

Event C2′ (when a CSI-RS resource set is better than a reference CSI-RSresource set by an offset or more)

The UE confirms:

1> whether the following specified condition C2-1′ is satisfied bytaking into consideration the following specified condition C2-1′ as theentry condition of an event;

1> whether the following specified condition C2-2′ is satisfied bytaking into consideration the following specified condition C2-2′ as theescape condition of an event;

Inequality C2-1′ (entry condition)

Mcr+Ocr−Hys>Mref+Oref+Off

Inequality C2-2′ (escape condition)

Mcr+Ocr+Hys<Mref+Oref+Off

The variables in the formula are defined as follows:

Mcr is a measured value of a CSI-RS resource set in which any offset isnot taken into consideration.

NOTE: In this case, Mcr may be derived through a measured value of oneor one or more CSI-RS resources included in a CSI-RS resource set, andmay have included multiple CSI-RS measurement values. The UE may deriveone Mcr using the multiple CSI-RS measurement values.

An example of methods that may be used to derive Mcr is described in theevent C1′.

Ocr is a CSI-RS resource set unique offset

Mref is a measured value of a reference CSI-RS resource set.

Oref is a unique offset value of a reference CSI-RS resource set.

Hys is a hysteresis parameter for a corresponding event, and Thresh is athreshold for the corresponding event.

Off is the parameter of the corresponding event

Mcr, Mref is represented in dBm.

Ocr, Oref, Hys, Off are represented in dB.

In an embodiment of the disclosure, an event that was a reference hasbeen written in the form of a CSI-RS resource set change event becauseis a CSI-RS-based event. A method for a UE to calculate the measurementresults (Mcr) of one CSI-RS resource set has various possibilities, andmethods that may be taken into consideration are as follows:

-   -   The mean or sum of measured values satisfying a given condition        (e.g., having a relative/absolute threshold or more) among N        best CSI-RS measurement values (L1/or L2/or L3 filtered)

The mean may be weighted averaging. A base station may transmit suchweight, N, filtering coefficient, etc. to a UE while transmitting ameasurement configuration.

Operation 719 and operation 720 are a procedure for the UE 700 to reportmeasurement to the base station 705 based on the preset condition. Atoperation 719, when the preset event condition is satisfied, the UE 700reports the measurement results to the measurement TRP 1 701. Atoperation 720, the TRP 1 701 reports the measurement results, receivedfrom the UE 700, to the base station 705. The corresponding measurementreport may be transmitted from the UE 700 to the base station 705 whenany condition (event) set by the base station 705 is satisfied or whenset periodicity is satisfied.

At operation 720, the base station 705 determines whether the UE 700needs to change a TRP based on the reported measurement information. Thedetermination method may be the same as the measurement reporttransmission event of the UE 700 or may be a base stationimplementation.

If a TRP change is not required at operation 722, the process proceedsto operation 724. At operation 724, the base station 705 does not needto provide the UE 700 with any information related to a TRP change.However, even in such a case, the UE 700 may need to change a beam beingused within the same TRP. In such a case, the base station 705 mayenable the UE 700 to perform a beam change.

If a TRP change is required at operation 722, the process proceeds tooperation 723. At operation 723 and operation 725, the base station 705transmits information for requesting a TRP change operation to the UE705. At operation 723, the base station 705 transmits the informationfor requesting (e.g., TRP change indication information) a TRP changeoperation to the TRP1 701. At operation 725, the TRP1 701 delivers theinformation for requesting a TRP change operation to the UE 700.

TRP change indication information (TRP change indication message) may bea physical layer message (PHY downlink control information), may be aMAC CE message, may be an IE included in an RRE message, for example, anRRC connection reconfiguration message. A corresponding TRP changesignal may include some or all of the following information.

-   -   TRP ID    -   CSI-RS resource set ID    -   NR-SS resource set ID    -   Beam set ID    -   Beam ID(s)    -   CSI-RS ID(s)    -   NR-SS ID(s)    -   Downlink resource scheduling including the CSI-RS, NR-SS of a        TRP being used or some or all of the following information        having an association relation with any beam or any antenna        configuration

->Quasi-co location (QCL) ID representing a beam association, providingnotification that a base station will transmit information using whichbeam as a corresponding resource

->a CSI RS ID having a QCL relation with a corresponding resource

->an NR-SS ID having a QCL relation with a corresponding resource

-   -   Downlink resource scheduling including the CSI-RS, NR-SS of a        target TRP to be changed in the future or some or all of the        following information having an association relation with any        beam or any antenna configuration

->Quasi-co location (QCL) ID representing a beam association, providingnotification that a base station will transmit information using whichbeam as a corresponding resource

->a CSI RS ID having a QCL relation with a corresponding resource

->an NR-SS ID having a QCL relation with a corresponding resource

-   -   Uplink resource scheduling including the CSI-RS, NR-SS of a        target TRP to be changed in the future or some or all of the        following information having an association relation with any        beam or any antenna configuration

->Quasi-co location (QCL) ID representing a beam association providingnotification that a base station will receive information using whatbeam as a corresponding resource

->a CSI RS ID having a QCL relation with a corresponding resource

->an NR-SS ID having a QCL relation with a corresponding resource

At operation 726, the TRP1 701 transmits UE information to the centralunit of the base station 705. If all contents have been previouslyincluded in the measurement report at operation 720, operation 726 is anoperation that may be omitted. The UE information that may betransmitted at operation 726 or operation 720 may be some or all of thefollowings.

A UE ID, a UE best beam/CSI-RS/NR-SS ID, the best beam of the TRP 2measured by the UE/CSI-RS/NR-SS ID and a measured value, MACinformation, RLC information, TRP2 timing advance measurementinformation of the UE, etc.

Operation 727 is an operation for the base station 705 to prepare theTRP2 702 for the joining of the UE 700, and is an operation that may beomitted if the TRP2 702 includes only a simple RF stage or antenna. UEinformation that may be transmitted at operation 727 may be some or allof the followings.

-   -   A UE ID, a UE best beam/CSI-RS/NR-SS ID, the best beam of the        TRP 2 measured by the UE/CSI-RS/NR-SS ID and a measured value,        MAC information, RLC information, TRP2 timing advance        measurement information of the UE, etc.

At operation 731, the UE 700 prepares to receive information of a targetTRP, the TRP 2, included in the corresponding TRP change indicationinformation, over a fixed time after the TRP change indicationinformation is received at operation 725 or until a scheduled resourceis received. The UE 700 changes a reception configuration so that thereception beam of the UE 700 is suitable for the reception of thedownlink resource of the TRP2 included in the TRP change indicationinformation and a beam/CSI-RS/NR-SS having a beam association (QCL)relation with the corresponding resource.

At operation 732, the TRP2 702 prepares to transmit a signal to a UE,included in the TRP change indication information, over a fixed timeafter the TRP change indication information is received.

At operation 733, the TRP1 701 flushes information on the UE 700.

At operation 734, the TRP2 prepares downlink transmission as alreadyallocated to the UE. A method for the base station to determine downlinkinformation to be transmitted and transmitted information, and theoperation of the UE may include some or all of the following operationsand transmission information.

Information 1) an RACH execution indicator or an RACH resourceallocation method

If a given UE needs to change a given TRP (or CSI-RS resource set, orNR-SS resource set, or beam set), the TRP2 (or base station) maytransmit both or one or more of an indicator indicative of RACHexecution in order to obtain new TRP uplink synchronization or adedicated RACH configuration through a downlink signal that transmits acorresponding change to the UE.

The corresponding RACH configuration may have included some or all oftypes of information of a target TRP (or CSI-RS resource set, or NR-SSresource set, or beam set) to be changed, for example, a TRP ID, a TRPtransmission CSI-RS ID, an NR-SS ID.

The base station measures the signal (UL SRS, UL CSI-RS, UL SR, . . . ),transmitted by the UE, through a different beam/TRP/beam belonging to aTRP. If one or more of the following conditions are satisfied, the basestation may determine that RACH execution is necessary for a TRP changefor the corresponding UE. The base station may include an indicator in adownlink signal in order to denote the execution of an RACH, maytransmit the indicator and an RACH configuration or may simply transmitthe RACH configuration or may transmit only a difference between an RACHconfiguration being used and an RACH configuration to be changed.

i. When a probability that the uplink synchronization of the UE will bebroken is a given threshold or more if the UE changes a current uplinktransmission beam pair (UE beam-base station beam) to a new transmissionbeam pair

ii. If the UE changes an uplink transmission beam pair (UE beam-basestation beam) being used to a new transmission beam pair, when theuplink synchronization timing advance (timing advance difference) valuebetween the two different beam pairs is a given threshold or more

The UE that has received RACH-related information transmitted by thebase station may immediately perform information transmission to a newTRP using the corresponding RACH information or after a given time setby the base station elapses.

Information 2) TA modification request information and modificationvalue

If a given UE needs to change a given TRP (or CSI-RS resource set, orNR-SS resource set, or beam set), a base station may check a differencebetween a timing advance value, measured using a target TRP (or CSI-RSresource set, or NR-SS resource set, or beam set) that may change agiven signal (e.g., SRS signal, UL RS signal) transmitted by thecorresponding UE, and a TRP (or CSI-RS resource set, or NR-SS resourceset, or beam set) value being used in a conventional technology in orderto obtain uplink synchronization, and may transmit the correspondingtiming advance difference or the timing advance value of the TRP througha downlink signal in which a corresponding change is transmitted to theUE. The base station may include an indicator in the downlink signal inorder to indicate that a TA should be modified, may transmit theindicator and a TA value or may simply transmit the TA value or maytransmit a difference between a TA value being used and a TA value to bechanged.

Target TRP (or CSI-RS resource set, or NR-SS resource set, or beam set)information to be changed, for example, some or all of the followinginformation may have been included in the corresponding timing advanceconfiguration value.

-   -   TRP ID    -   beam RS set ID    -   CSI-RS resource set ID    -   NR-SS resource set ID    -   beam ID(s))    -   CSI-RS ID(s)    -   NR-SS ID(s)    -   Downlink resource scheduling including the CSI-RS, NR-SS of a        beam RS set being used or some or all of the following        information having an association relation with any beam or any        antenna configuration

′Quasi-co location (QCL) ID representing a beam association, providingnotification that a base station will transmit information using whatbeam as a corresponding resource

′CSI RS ID having a QCL relation with a corresponding resource

′NR-SS ID having a QCL relation with a corresponding resource

-   -   Downlink resource scheduling including the CSI-RS, NR-SS of a        target beam RS set to be changed in the future or some or all of        the following information having an association relation with        any beam or any antenna configuration

′Quasi-co location (QCL) ID representing a beam association, providingnotification that a base station will transmit information using whatbeam as a corresponding resource

′CSI RS ID having a QCL relation with a corresponding resource

′NR-SS ID having a QCL relation with a corresponding resource

-   -   Uplink resource scheduling including the CSI-RS, NR-SS of a        target beam RS set to be changed in the future or some or all of        the following information having an association relation with        any beam or any antenna configuration

′Quasi-co location (QCL) ID representing a beam association, providingnotification that a base station will receive information using whatbeam as a corresponding resource

′CSI RS ID having a QCL relation with a corresponding resource

′NR-SS ID having a QCL relation with a corresponding resource

In addition to the method for the TRP to directly provide the UE with(dedicated signal) information, a base station may provide thattransmission and reception between TRPs needs to be changed as a networkcommon signal.

In an embodiment, a base station includes information in a referencesignal (RS), transmitted by a different TRP, in the form of an indicator(or group ID). A UE may read the RS and perform a TA change or RACH onlywhen transmission and reception between corresponding TRPs (or TRPsbelonging to a different group) is changed.

In another embodiment, a base station may transmit an indicator,indicating that a TA change or RACH execution is necessary, through abroadcasting signal (or multicasting signal) only when UE transmissionand reception between different TRPs is changed.

At operation 735, the UE 700 starts communication with the TRP2 702based on the TRP change indication information and the message receivedfrom the TRP2 702. In this case, transmittable information may havevarious form, and may include a response message or acknowledge messagefor the downlink transmission of the TRP 2 or RACH preamble signaltransmission.

The TRP1 701 and the TRP2 702 may be substituted with CSI-RS resourceset1 and set2, NR-SS resource set1 and 2, or beam set1 and set2, or basestation antenna configuration set1 and set2 and applied and used.

FIG. 8 is a diagram showing a method for a base station to change a beamRS set (CSI/RS resource set/NR-SS resource set/beam resource set/antennaconfiguration set) through the RS measurement of a terminal in anembodiment of the disclosure.

Referring to FIG. 8, a system may include a UE 800 and a base station805. First, the UE 800 is a UE belonging to the base station 805, andexchanges information with the base station 805 using a beam RS set1.The UE 800 may have explicitly recognized that it uses the beam RS settusing the ID of the beam RS set1 or may not explicitly recognize that ituses the beam RS set1 or may have recognized that it performscommunication with the base station using any beams belonging to thebeam RS set1, for example, a CSI-RS resource set, an NR-SS resource set,a TRP antenna Tx/Rx configuration or any beam set. The beam RS sett maycorrespond to a TRP 1.

At operation 811, the base station 805 selects RSs to be transmitted bythe beam RS set1 and a beam RS set2 and the resources of thecorresponding RSs so that the corresponding UE 800 can performmeasurement, and schedules a resource in which the corresponding RSswill be transmitted in advance with respect to the UE.

At operation 812 and operation 813, the base station 805 transmits theRSs to the corresponding UE 802, as allocated, for measurement. Atoperation 812, the base station may transmit the RS corresponding to thebeam RS set 1. At operation 813, the base station may transmit the RScorresponding to the beam RS set 2. The beam RS set 2 may correspond toa TRP 2.

At operation 814, the UE 800 performs RS measurement on the differentbeam RS sets, and updates measurement information for filteringpurposes, for example, if necessary.

At operation 815, a network may configure RRM measurement bytransmitting an RRC connection reconfiguration message for the beam RSset measurement and report of the UE, and may configure measurementreport transmission. The message of operation 815 may include the RSscheduling message of operation 811. The measurement event configurationof operation 815 may be included in the RS scheduling message ofoperation 811. A measurement report transmission event of the UE thatmay be taken into consideration may be the A1˜A6 events of the LTEstandard or may be the C1, C2 events or may be the C1′ and C2′ eventsmodified from the existing C1 and C2 events and described in FIG. 7.

Operation 816 is a procedure for the UE 800 to report measurement to thebase station based on a condition configured at operation 815. Thecorresponding measurement report may be transmitted from the UE to thebase station when any condition (event) configured by the base stationis satisfied or set periodicity is satisfied.

At operation 817, the base station determines whether the UE needs tochange a beam RS set based on the reported measurement information. Thedetermination method may be the same as the measurement reporttransmission event of the UE or may be a base station implementation.

If a beam RS set change is not required at operation 818, the basestation 805 does not need to provide the UE 800 with any informationrelated to the beam RS set change. However, even in such a case, the UE800 may need to change a beam being used within the same beam RS set. Insuch a case, the base station 805 may enable the UE 800 to perform abeam change.

If it is determined that a beam RS set change is required at operation818, the process proceeds to operation 819. At operation 819, the basestation 805 transmits information for requesting a beam RS set changeoperation to the UE 800 as the beam RS set change is changed. The beamRS set change signal (beam RS set change indication message) may be aphysical layer message (PHY downlink control information), may be a MACCE message, may be an IE included in an RRE message, for example, an RRCconnection reconfiguration message. The corresponding beam RS set changesignal may include some or all of the following information.

-   -   beam RS set ID    -   CSI-RS resource set ID    -   NR-SS resource set ID    -   beam ID(s)    -   CSI-RS ID(s)    -   NR-SS ID(s)    -   Downlink resource scheduling including the CSI-RS, NR-SS of a        beam RS set being used or some or all of the following        information having an association relation with any beam or any        antenna configuration

′ Quasi-co location (QCL) ID representing a beam association, providingnotification that a base station will transmit information using whatbeam as a corresponding resource

′CSI RS ID having a QCL relation with a corresponding resource

′NR-SS ID having a QCL relation with a corresponding resource

-   -   Downlink resource scheduling including the CSI-RS, NR-SS of a        target beam RS set to be changed in the future or some or all of        the following information having an association relation with        any beam or any antenna configuration

′ Quasi-co location (QCL) ID representing a beam association, providingnotification that a base station will transmit information using whatbeam as a corresponding resource

′CSI RS ID having a QCL relation with a corresponding resource

′NR-SS ID having a QCL relation with a corresponding resource

-   -   Uplink resource scheduling including the CSI-RS, NR-SS of a        target beam RS set to be changed in the future or some or all of        the following information having an association relation with        any beam or any antenna configuration

′ Quasi-co location (QCL) ID representing a beam association, providingnotification that a base station will receive information using whatbeam as a corresponding resource

′CSI RS ID having a QCL relation with a corresponding resource

′NR-SS ID having a QCL relation with a corresponding resource

At operation 820, the UE 800 changes a reception configuration so thatthe reception beam of the UE is suitable for the reception of thedownlink resource of the beam RS set2 included in the beam RS set changeindication information and a beam/CSI-RS/NR-SS having a beam association(QCL) relation with the corresponding resource in order to prepare toreceive information of the target beam RS set2 included in thecorresponding beam RS set change indication information over a fixedtime after the beam RS set change indication information is received atoperation 819 or a scheduled resource.

At operation 821, the beam RS set2 prepares downlink transmission asalready allocated to the UE 800. Transmittable downlink information mayhave included some or all of the following information.

-   -   A beam RS set2 connection grant, timing Advance change        information, RACH request information, etc.

At operation 822, the UE 800 starts communication using some or all ofthe beams of the beam RS set2 based on the beam RS set change indicationinformation and the message received from the beam RS set2. In thiscase, transmittable information may have various form, and may include aresponse message or acknowledge message or RACH preamble signaltransmission for the downlink transmission of the beam RS set2.

The beam RS sett and the beam RS set2 may be substituted with CSI-RSresource set1 and set2, NR-SS resource set1 and 2, beam set1 and set2, aTRP1 and a TRP2, or base station antenna configuration set1 and set2 andapplied and used.

FIG. 9 is a diagram showing a TRP change method when a base stationcontrols the mobility of a terminal in an embodiment of the disclosure.

Referring to FIG. 9, a system may include a UE 900, a TRP 1 901, a TRP 2902 and a base station 905.

The UE 900 is a UE belonging to the base station 905 and exchangesinformation with the base station using the TRP1 901. The UE 900 mayhave explicitly recognized that it uses the TRP1 901 using the ID of theTRP1 901 or may not explicitly recognize that it uses the TRP1 901 andmay recognize that it performs communication with the base station usingany beams belonging to the TRP1 901, for example, a CSI-RS resource set,an NR-SS resource set, a TRP antenna Tx/Rx configuration or a given beamset.

At operation 911 and operation 912, the base station 905 selects RSs tobe transmitted by the TRP1 901 and the TRP2 902 and the resources of thecorresponding RSs so that the UE 900 can perform measurement, anddelivers such information to the TRP1 901 and the TRP2 902 if theinformation needs to be provided to the TRPs. In this case, the TRP1 901needs to schedule RS information of the TRP2 902 with respect to the UE900 in addition to the RS of the TRP1 901. Accordingly, the base station905 may provide the TRP1 901 with both RS configuration information ofthe TRP1 901 and configuration information of the TRP2 902.

At operation 913, the TRP1 901 provides the UE 900 with the configuredresource configuration information of the TRP1 901 and the TRP2 902 sothat the UE 900 can measure each of the TRPs. In this case, a direct TRPID associated with resource configuration information of a different TRPmay be provided or any resource segmentation method of enabling the UEto indirectly distinguish between the TRPs, for example, a method oftransmitting the RSs of different TRPs at time intervals may be used sothat the UE 900 can recognize that the corresponding RSs are transmittedby different TRPs.

At operation 914, the TRP1 901 transmits the RS to the UE 900, asallocated, for measurement. At operation 915, the TRP2 902 transmits theRS to the UE 900, as allocated, for measurement.

At operation 916, the UE 900 performs RS measurement on different TRPs,and updates measurement information for filtering purposes, for example,if necessary.

At operation 917, the TRP 1 901 may indicate that beam measurementresults should be reported. The TRP 1 901 may indicate that the bestbeam or N beams having good performance should be reported for each TRP.The beam measurement result report information may indicate thatinformation on a TRP ID, a beam ID, beam quality should be reported.

At operation 918, the UE 900 may report beam measurement results. The UE900 may report the beam measurement results to the TRP 1 901. The beammeasurement results may include the best beam for each TRP or N beamshaving good performance for each TRP, and may also include IDinformation of the UE.

At operation 919, the TRP1 901 transmits the feedback information,received from the UE 900, to the base station 905. The TRP1 901 maytransmit the ID information of the UE and information on the best beamfor each TRP or the N beams having good performance for each TRP to thebase station 905.

At operation 920, the base station 905 may determine whether a TRPchange is required. The base station 905 may determine whether a TRPchange is required based on information received from the TRP1 901. Thedetermination method may be the same as a measurement reporttransmission event. For example, when the measurement results of thereference signal of the TRP2 is greater than the measurement results ofthe reference signal of the TRP1 by a value of a preset offset, the basestation may determine that a TRP change is required.

If it is determined that a TRP change is not required at operation 921,the process proceeds to operation 922. If it is determined that a TRPchange is required, the process proceeds to operation 923.

At operation 922, the base station 905 does not need to provide the UE900 with any information related to a TRP change. However, even in sucha case, the UE 900 may need to change a beam being used within the sameTRP. In such a case, the TRP1 901 may enable the UE 900 to perform abeam change.

At operation 923, the base station 905 transmits information forrequesting (e.g., TRP change indication information) a TRP changeoperation to the TRP1 901. At operation 924, the TRP1 901 transmits theinformation for requesting a TRP change operation to the UE 900. TRPchange indication information (TRP change indication message) may be aphysical layer message (PHY downlink control information), may be a MACCE message, may be an IE included in an RRE message, for example, an RRCconnection reconfiguration message. For a detailed example that may beincluded in the corresponding TRP change signal, reference is made tothe embodiment of FIG. 7.

At operation 926, the TRP1 901 transmits UE information to the centralunit of the base station 905. If all contents have been previouslyincluded in the measurement report at operation 919, operation 926 is anoperation that may be omitted. The UE information that may betransmitted at operation 926 or operation 919 may be some or all of thefollowings.

A UE ID, a UE best beam/CSI-RS/NR-SS ID, the best beam of the TRP 2measured by the UE/CSI-RS/NR-SS ID and a measured value, MACinformation, RLC information, TRP2 timing advance measurementinformation of the UE, etc.

Operation 927 is an operation for the base station 905 to prepare theTRP2 902 for the joining of the UE 900, and is an operation that may beomitted if the TRP2 902 includes only a simple RF stage or antenna. Atoperation 927, UE information that may be transmitted may be some or allof the followings.

-   -   A UE ID, a UE best beam/CSI-RS/NR-SS ID, the best beam of the        TRP 2 measured by the UE/CSI-RS/NR-SS ID and a measured value,        MAC information, RLC information, TRP2 timing advance        measurement information of the UE, etc.

At operation 931, the UE 900 prepares to receive information of a targetTRP, the TRP 2 included in the corresponding TRP change indicationinformation over a fixed time after the TRP change indicationinformation is received at operation 924 or until a scheduled resourceis received. The UE 900 changes a reception configuration so that itsown reception beam is suitable for the reception of the downlinkresource of the TRP2 902 included in the TRP change indicationinformation and a beam/CSI-RS/NR-SS having a beam association (QCL)relation with the corresponding resource.

At operation 932, the TRP2 902 prepares to transmit a signal to the UE900, included in the TRP change indication information, over a fixedtime after the TRP change indication information is received.

At operation 933, the TRP1 901 flushes information on the UE 900.

Thereafter, the UE 900 and the TRP2 902 may perform communication.

FIG. 10 is a diagram showing a procedure of changing a TRP after a grantin an embodiment of the disclosure.

Referring to FIG. 10, a system may include a UE 1000, a TRP 1 1001, aTRP 2 1002 and a base station 1005. The UE 1000 is a UE belonging to thebase station 1005, and exchanges information with the base station usingthe TRP1 1001.

Operation 1011 to operation 1023 of FIG. 10 correspond to the contentsof operation 911 to operation 923 of FIG. 9. For them, reference is madeto the related contents of FIG. 9.

At operation 1023, the base station 1005 transmits information forrequesting (e.g., TRP change indication information) a TRP changeoperation to the TRP1 1001. At operation 1024, the TRP1 1001 transmitsUE information to the central unit of the base station 1005. If all thecontents have been previously included in the measurement report atoperation 1019, operation 1024 is an operation that may be omitted. Atoperation 1024 or operation 1019, the UE information that may betransmitted may be some or all of the followings.

A UE ID, a UE best beam/CSI-RS/NR-SS ID, the best beam of the TRP 2measured by the UE/CSI-RS/NR-SS ID and a measured value, MACinformation, RLC information, TRP2 timing advance measurementinformation of the UE, etc.

Operation 1025 is an operation for the base station 1005 to prepare theTRP2 1002 for the joining of the UE 1000, and is an operation that maybe omitted if the TRP2 1002 includes only a simple RF stage or antenna.UE information that may be transmitted at operation 1025 may be some orall of the followings.

-   -   A UE ID, a UE best beam/CSI-RS/NR-SS ID, the best beam of the        TRP 2 measured by the UE/CSI-RS/NR-SS ID and a measured value,        MAC information, RLC information, TRP2 timing advance        measurement information of the UE, etc.

At operation 1026, the TRP2 1002 may transmit a response message for aTRP change request to the base station 1005. The TRP2 1002 may transmitinformation indicative of a TRP change grant or a TRP change denial.

At operation 1027, the base station 1005 may deliver a response messagefor a TRP change request to the TRP1 1001. The response message mayinclude information for granting a TRP change or information for denyinga TRP change depending on whether the TRP2 1002 grants a TRP change.

When information to grant a TRP change is received, at operation 1028,the TRP1 1001 transmits information for requesting (e.g., TRP changeindication information) a TRP change operation to the UE 1000. The TRPchange indication information (TRP change indication message) may be aphysical layer message (PHY downlink control information), may be a MACCE message, may be an IE included in an RRE message, for example, an RRCconnection reconfiguration message.

Operation 1031 to operation 1033 of FIG. 10 correspond to operation 931to operation 933 of FIG. 9. For them, reference is made to thedescription of FIG. 9.

FIG. 11 is a diagram showing a procedure of changing a TRP after a grantin another embodiment of the disclosure.

Referring to FIG. 11, a system may include a UE 1100, a TRP 1 1101, aTRP 2 1102 and a base station 1105. The UE 1100 is a UE belonging to thebase station 1105, and exchanges information with the base station usingthe TRP1 1101.

Operation 1111 to operation 1118 of FIG. 11 correspond to operation 1011to operation 1018 of FIG. 10. For them, reference is made to the relatedcontents of FIG. 10.

At operation 1119, the TRP1 1101 transmits feedback information,received from the UE 1100, to the base station 1105. The TRP1 1101 maytransmit ID information of the UE and information on the best beam foreach TRP or N beams having good performance for each TRP to the basestation 1105.

At operation 1119-2, the TRP1 1101 transmits the UE information to thecentral unit of the base station 1105. If all the contents have beenpreviously included in the measurement report at operation 1119,operation 1119-2 is an operation that may be omitted. UE informationthat may be transmitted at operation 1119 or operation 1119-2 may besome or all of the followings.

-   -   A UE ID, a UE best beam/CSI-RS/NR-SS ID, the best beam of the        TRP 2 measured by the UE/CSI-RS/NR-SS ID and a measured value,        MAC information, RLC information, TRP2 timing advance        measurement information of the UE, etc.

Operation 1119 and Operation 1119-2 may be formed of one transmissionoperation.

Operation 1120 to operation 1123 of FIG. 11 correspond to operation 1020to operation 1023 of FIG. 10. For them, reference is made to the relateddescription of FIG. 10. In FIG. 11, an operation corresponding tooperation 1024 of FIG. 10 has been omitted. An operation correspondingto operation 1024 has been performed at operation 1119-2.

Operation 1125 to operation 1133 of FIG. 11 correspond to operation 1025to operation 1033 of FIG. 10. For them, reference is made to the relatedoperations of FIG. 10.

FIG. 12 is a diagram showing a procedure of changing a TRP based on anRRC message in another embodiment of the disclosure.

Referring to FIG. 12, a system may include a UE 1200, a TRP 1 1201, aTRP 2 1202 and a base station 1205. The UE 1200 is a UE belonging to thebase station 1205, and exchanges information with the base station usingthe TRP1 1201.

Operation 1211 to operation 1233 of FIG. 12 correspond to operation 711to operation 733 of FIG. 7. For them, reference is made to the relatedcontents of FIG. 7.

At operation 1234, the UE 1200 transmits an RRC connection requestmessage to the TRP2 1202. That is, the UE 1200 receives TRP changeindication information from the base station 1205 or the TRP1 1201, andtransmits the RRC connection request message to a TRP (TRP2 1202 in theembodiment of FIG. 12) for which a TRP change has been indicated inresponse thereto.

At operation 1235, the TRP2 1202 transmits an RRC connection responsemessage to the UE 1200 in response to the reception of the RRCconnection request. A TRP change using the RRC message may be performeddepending on operation 1234 and operation 1235.

<Information Exchange Method Between TRP-CU>

1. A TRP may exchange and share UE information (MAC context, RLCcontext, timer information, buffer information, . . . ) with a CU andother TRPs in real time.

A. Information sharing between TRPs may be performed through a CU usingan interface between the CU and the TRP.

B. Information sharing between TRPs may be performed using an interfacebetween TRPs directly connected between the TRPs.

2. A CU may receive UE information from one TRP and manage the UEinformation, and may share it with other TRPs when the TRPs require theUE information (when a TRP change is necessary).

FIG. 13 is a diagram showing a method of exchanging UE informationbetween a TRP and a base station according to an embodiment of thedisclosure.

Referring to FIG. 13, a system may include a UE 1300, a TRP1 1301, aTRP2 1302, a TRP k 1303, and a base station 1305. The UE 1300 is a UEbelonging to the base station 1305, and exchanges information with thebase station 1305 using the TRP1 1301.

At operation 1311, the UE 1300 transmits feedback information to theTRP1 1301. The feedback information may include TRP information, beaminformation, RACH information, SR information, etc. Furthermore, thefeedback information may include UE information (MAC context, RLCcontext, timer information, buffer information, . . . ).

At operation 1312, the TRP1 1301 may transmit UE information to the basestation 1305. The UE information may be UE context information. The UEinformation may include MAC context, RLC context, timer information,buffer information, . . . .

At operation 1313, the base station 1305 may transmit the UEinformation, received from the TRP1 1301, to the TRP2 1302. At operation1314, the base station 1305 may transmit the UE information, receivedfrom the TRP1 1301, to the TRP k 1303.

As described above, UE information may be delivered to another TRP usingan interface between the base station 1305 and the TRP.

FIG. 14 is a diagram showing a method of exchanging UE informationbetween a TRP and a base station according to another embodiment of thedisclosure.

Referring to FIG. 14, a system may include a UE 1400, a TRP1 1401, aTRP2 1402, a TRP k 1403, and a base station 1405. The UE 1400 is a UEbelonging to the base station 1405, and exchanges information with thebase station 1405 using the TRP1 1401.

At operation 1411, the UE 1400 transmits feedback information to theTRP1 1401. The feedback information may include TRP information, beaminformation, RACH information, SR information, etc. Furthermore, thefeedback information may include UE information (MAC context, RLCcontext, timer information, buffer information, . . . ).

At operation 1412, the TRP1 1401 may transmit UE information to the basestation 1405. The UE information may be UE context information. The UEinformation may include MAC context, RLC context, timer information,buffer information, . . . .

At operation 1413, the TRP1 1401 may transmit the UE information to theTRP2 1402. At operation 1414, the TRP1 1401 may transmit the UEinformation to the TRP k 1403.

As described above, information sharing between TRPs may be performedusing an interface between TRPs directly connected between the TRPs.

FIG. 15 is a diagram showing a method of sharing UE information when aTRP change is requested in an embodiment of the disclosure.

Referring to FIG. 15, a system may include a UE 1500, a TRP1 1501, aTRP2 1502, a TRP k 1503, and a base station 1505. The UE 1500 is a UEbelonging to the base station 1505, and exchanges information with thebase station 1505 using the TRP1 1501.

At operation 1511, the UE 1500 transmits feedback information to theTRP1 1501. The feedback information may include TRP information, beaminformation, RACH information, SR information, etc. Furthermore, thefeedback information may include UE information (MAC context, RLCcontext, timer information, buffer information, . . . ).

At operation 1512, the TRP1 1501 determines whether a TRP change isrequired. For a method of determining a TRP change, reference is made tothe determination methods described in the previous embodiments.

If a TRP change is not required, at operation 1513, the TRP1 1501 doesnot need to provide the UE 1500 with any information related to a TRPchange. However, even in such a case, the UE 1500 may need to change abeam being used within the same TRP. In such a case, the TRP1 1501 orthe base station 1505 may enable the UE 1500 to perform a beam change.

At operation 1514, the TRP1 1501 transmits information for requesting aTRP change operation to the base station 1505. The information forrequesting (e.g., TRP change indication information) a TRP changeoperation may be a physical layer message (PHY downlink controlinformation), may be a MAC CE message, may be an IE included in an RREmessage, for example, an RRC connection reconfiguration message. For thecontents of information that may be included in the TRP changeindication information, reference is made to the embodiment of FIG. 7.

At operation 1515, the base station 1505 transmits the information forrequesting a TRP change operation to the TRP 2 1502, that is, thesubject of a TRP change. In the embodiment, the base station 1505transmits the information for requesting a TRP change operation to theTRP2 1502 because it is assumed that a TRP for the UE 1500 is changedfrom the TRP1 1501 to the TRP2 1502.

FIG. 16 is a diagram showing a method of sharing UE information when aTRP change is requested in another embodiment of the disclosure.

Referring to FIG. 16, a system may include a UE 1600, a TRP1 1601, aTRP2 1602, a TRP k 1603, and a base station 1605. The UE 1600 is a UEbelonging to the base station 1605, and exchanges information with thebase station 1605 using the TRP1 1601.

At operation 1611, the UE 1600 transmits feedback information to theTRP1 1601. The feedback information may include TRP information, beaminformation, RACH information, SR information, etc. Furthermore, thefeedback information may include UE information (MAC context, RLCcontext, timer information, buffer information, . . . ).

At operation 1612, the TRP1 1601 determines whether a TRP change isrequired. For a method of determining a TRP change, reference is made tothe determination methods described in the previous embodiments.

If a TRP change is not required, at operation 1613, the TRP1 1601 doesnot need to provide the UE 1600 with any information related to a TRPchange. However, even in such a case, the UE 1600 may need to change abeam being used within the same TRP. In such a case, the TRP1 1601 orthe base station 1605 may enable the UE 1600 to perform a beam change.

At operation 1614, the TRP1 1601 transmits information for requesting aTRP change operation to the base station 1605. The information (e.g.,TRP change indication information) for requesting a TRP change operationmay be a physical layer message (PHY downlink control information), maybe a MAC CE message, may be an IE included in an RRE message, forexample, an RRC connection reconfiguration message. For the contents ofinformation that may be included in the TRP change indicationinformation, reference is made to the embodiment of FIG. 7.

At operation 1615, the TRP1 1601 transmits the information forrequesting a TRP change operation to the TRP 2 1602, that is, thesubject of a TRP change. In the embodiment, the TRP1 1601 transmits theinformation for requesting a TRP change operation to the TRP2 1602because it is assumed that a TRP for the UE 1600 is changed from theTRP1 1601 to the TRP2 1602.

FIG. 17 is a diagram showing a method of sharing UE information when aTRP change is requested in another embodiment of the disclosure.

Referring to FIG. 17, a system may include a UE 1700, a TRP1 1701, aTRP2 1702, a TRP k 1703, and a base station 1705. The UE 1700 is a UEbelonging to the base station 1705, and exchanges information with thebase station 1705 using the TRP1 1701.

At operation 1711, the UE 1700 transmits feedback information to theTRP1 1701. The feedback information may include TRP information, beaminformation, RACH information, SR information, etc. Furthermore, thefeedback information may include UE information (MAC context, RLCcontext, timer information, buffer information, . . . ).

At operation 1712, the TRP1 1701 may transmit UE information to the basestation 1705. The UE information may be UE context information. The UEinformation may include MAC context, RLC context, timer information,buffer information, . . . .

At operation 1713, the base station 1705 determines whether a TRP changeis required. For a method of determining a TRP change, reference is madeto the determination methods described in the previous embodiments.

If a TRP change is not required, at operation 1714, the base station1705 does not need to provide the UE 1700 with any information relatedto a TRP change. However, even in such a case, the UE 1700 may need tochange a beam being used within the same TRP. In such a case, the basestation 1705 may enable the UE 1700 to perform a beam change.

If a TRP change is required, at operation 1715, the base station 1705transmits information for requesting a TRP change operation to the TRP21602. The information (e.g., TRP change indication information) forrequesting a TRP change operation may be a physical layer message (PHYdownlink control information), may be a MAC CE message, may be an IEincluded in an RRE message, for example, an RRC connectionreconfiguration message. For the contents of information that may beincluded in the TRP change indication information, reference is made tothe embodiment of FIG. 7.

FIG. 18 is a diagram showing a UE feedback trigger and TRP change methodaccording to an event in an embodiment of the disclosure.

Referring to FIG. 18, a system may include a UE 1800, a TRP 1 1801, aTRP 2 1802 and a base station 1805.

The UE 1800 is a UE 1800 belonging to the base station 1805, andexchanges information with the base station using the TRP1 1801.

At operation 1811 and operation 1812, the base station 1805 selects RSsto be transmitted by the TRP1 1801 and the TRP2 1802 and the resourcesof the corresponding RSs so that the UE 1800 can measure the TRPs, anddelivers such information to the TRP1 1801 and the TRP2 1802 if theinformation needs to be provided to the TRPs. In this case, the TRP11801 has to schedule RS information of the TRP2 1802 in addition to theRS of the TRP1 1801 with respect to the UE 1800. Accordingly, the basestation 1805 may provide the TRP1 1801 with both RS configurationinformation of the TRP1 1801 and configuration information of the TRP21802.

At operation 1813, the TRP1 1801 provides the UE 1800 with theconfigured resource configuration information of the TRP1 1801 and theTRP2 1802 so that the UE 1800 can measure each of the TRPs. In thiscase, the TRP 1 1801 may provide a direct TRP ID associated withresource configuration information of a different TRP or any resourcesegmentation method of enabling the UE to indirectly distinguish betweenthe TRPs, for example, a method of transmitting the RSs of differentTRPs at time intervals may be used so that the UE 1800 can recognizethat the corresponding RSs are transmitted by different TRPs.

At operation 1814, the TRP1 1801 transmits the RS to the UE 1800, asallocated, for measurement. At operation 1815, the TRP2 1802 transmitsthe RS to the UE 1800, as allocated, for measurement.

At operation 1816, the UE 1800 performs RS measurement on differentTRPs, and updates measurement information for filtering purposes, forexample, if necessary.

At operation 1817, the TRP1 1801 may indicate that beam measurementresults should be reported. The TRP 1 1801 may indicate that the bestbeam or N beams having good performance should be reported for each TRP.The beam measurement result report information may indicate thatinformation on a TRP ID, a beam ID, beam quality should be reported.

At operation 1818, the UE 1800 checks whether a feedback event has beentriggered. If a feedback event has not been triggered, at operation1819, the UE 1800 does not perform an operation for feedback. If afeedback event has been triggered, at operation 1820, the UE 1800transmits feedback information to the TRP1 1801. The information may betransmitted using a pre-scheduled resource, RACH resource, SR resource,other possible resource, etc.

At operation 1821, the TRP1 1801 may determine whether a TRP change isrequired. The TRP1 1801 may determine whether a TRP change is requiredbased on reported measurement results. For example, if the measurementresults of the reference signal of the TRP2 is greater than themeasurement results of the reference signal of the TRP1 by a value of apreset offset, the TRP1 1801 may determine that a TRP change isrequired.

If it is determined that a TRP change is not required at operation 1822,the process proceeds to operation 1823. If it is determined that a TRPchange is required, the process proceeds to operation 1824.

At operation 1823, the TRP1 1801 does not need to provide the UE 1800with any information related to a TRP change. However, even in such acase, the UE 1800 may need to change a beam being used within the sameTRP. In such a case, the TRP1 1801 may enable the UE 1800 to perform abeam change.

At operation 1824, the TRP1 1801 transmits information (e.g., TRP changeindication information) for requesting a TRP change operation to the UE1800. At operation 1824, the TRP1 1801 transmits the information forrequesting a TRP change operation to the UE 1800.

At operation 1825, the TRP1 1801 provides a TRP change request and UEinformation to the base station 1805. There is a need for a procedure ofnotifying the base station 1805 of information indicating that a TRPchange is necessary because the TRP1 1801 has determined the TRP change.The information may include at least one of a UE ID, a UE bestbeam/CSI-RS/NR-SS ID, the best beam of the TRP 2 measured by theUE/CSI-RS/NR-SS ID and a measured value, MAC information, RLCinformation, or TRP2 timing advance measurement information of the UE.

At operation 1826, the base station 1805 may provide the TRP2 1802 withthe TRP change request and UE information. The TRP2 1802 may prepare thejoining of the UE based on the TRP change request and UE information.

At operation 1831, the UE 1800 prepares to receive information of atarget TRP, the TRP 2 included in a corresponding TRP change requestmessage over a fixed time after the TRP change request message isreceived or until a scheduled resource is received. The UE 1800 changesa reception configuration so that the reception beam of the UE issuitable for the reception of the downlink resource of the TRP2 includedin the TRP change request message and a beam/CSI-RS/NR-SS having a beamassociation (QCL) relation with the corresponding resource.

At operation 1832, the TRP1 1801 flushes information on the UE 1800.

At operation 1833, the TRP2 1802 prepares to transmit a signal to a UE,included in the TRP change request message, over a fixed time after theTRP change request message is received.

FIG. 19 is a diagram showing a terminal feedback trigger and TRP changemethod according to an event in another embodiment of the disclosure.

Referring to FIG. 19, a system may include a UE 1900, a TRP 1 1901, aTRP 2 1902 and a base station 1905. The UE 1900 is a UE 1900 belongingto the base station 1905, and exchanges information with the basestation using the TRP1 1901.

Operation 1911 to operation 1917 of FIG. 19 correspond to operation 1811to operation 1817 of FIG. 18. For them, reference is made to the relateddescription of FIG. 18.

At operation 1918, the UE 1900 determines whether a TRP change event hasbeen triggered. If a TRP change event has not been triggered, atoperation 1919, the UE 1900 does not perform an operation for a TRPchange.

If a TRP change event has been triggered, at operation 1920, the UE 1900may transmit TRP change request information to the TRP2 1902. The UE1900 may transmit at least one of a TRP change request, a TRPreallocation request, or a TRP reconfiguration request. The request ofthe UE 1900 may be transmitted through a common channel or an RACHchannel or an allocated another uplink resource.

At operation 1921, the TRP2 1902 requests UE context from the basestation 1905. At operation 1922, the base station 1905 requests the UEcontext from the TRP1 1901.

At operation 1923, the TRP1 1901 transmits the UE context to the basestation 1905. The UE context may include beam information, best beaminformation, MAC context, RLC context, timer information, bufferinformation, etc.

At operation 1924, the base station 1905 may transmit TRP change requestinformation to the TRP2 1902.

At operation 1925, the TRP2 1902 transmits TRP change responseinformation to the UE 1900.

At operation 1931, the UE 1900 prepares to receive information of atarget TRP, the TRP 2, included in the corresponding TRP change requestmessage, over a fixed time after the TRP change request message isreceived or until a scheduled resource is received. The UE 1900 changesa reception configuration so that the reception beam of the UE issuitable for the reception of the downlink resource of the TRP2 includedin the TRP change request message and a beam/CSI-RS/NR-SS having a beamassociation (QCL) relation with the corresponding resource.

At operation 1932, the TRP1 1901 flushes information on the UE 1800.

At operation 1933, the TRP2 1902 prepares to transmit a signal to a UE,included in the TRP change request message, over a fixed time after theTRP change request message is received.

FIG. 20 is a diagram showing a terminal according to an embodiment ofthe disclosure.

Referring to FIG. 20, the UE may include a transceiver 2010 and acontroller 2030. The UE transmits and/or receives a signal, information,data, a message, etc. through the transceiver 2010. The controller 2030may include at least one processor. The controller 2030 may control anoverall operation of the UE.

In accordance with an embodiment of the disclosure, the controller 2030may control to receive resource configuration information, includingreference signal configuration information of a first TRP and referencesignal configuration information of a second TRP, from a firsttransmission and reception point (TRP), to measure a reference signalcorresponding to the first TRP and a reference signal corresponding tothe second TRP based on the resource configuration information, toreport the measurement information on the reference signal correspondingto the first TRP and the reference signal corresponding to the secondTRP to the first TRP, to receive TRP change indication information fromthe first TRP, and to change a configuration for the second TRP based onthe TRP change indication information. The TRP change indicationinformation may be included in a medium access control (MAC) controlelement (CE) message. The TRP change indication information may includea channel state information-reference signal (CSI-RS) for the secondTRP.

Furthermore, the controller 2030 may control to receive at least one ofconnection grant information, timing advance (TA) information or randomaccess channel (RACH) request information from the TRP2.

An operation of the controller 2030 is not limited thereto. In anembodiment of the disclosure, the controller 2030 may control theoperation of the UE described through the embodiments of FIGS. 1 to 19of the disclosure.

FIG. 21 is a diagram showing a base station according to an embodimentof the disclosure.

Referring to FIG. 21, the base station may include a transceiver 2110and a controller 2130. The transceiver 2110 of the base station may be aconcept including at least one TRP and or at least one antenna. Thecontroller 2130 of the base station may be a concept including at leastone CU and at least one DU. The base station may transmit and/or receivea signal, information, data, a message, etc. through the transceiver2110. The controller 2130 may include at least one processor. Thecontroller 2130 may control an overall operation of the base station.

In accordance with an embodiment of the disclosure, the transceiver 2110includes a first transmission and reception point (TRP) and a secondTRP. The controller 2130 may perform control to transmit resourceconfiguration information including reference signal configurationinformation of the first TRP and reference signal configurationinformation of the second TRP, to receive measurement report informationtransmitted by a UE, to determine whether the transceiver 2110transmitting and receiving information to and from the UE will bechanged from the first TRP to the second TRP, to transmit TRP changeindication information to the UE using the first TRP, to provideadditional information enabling the UE to easily access the second TRPif necessary, and to resume communication with the UE through the secondTRP. The TRP change indication information may be included in a mediumaccess control (MAC) control element (CE) message. The TRP changeindication information may include a channel state information-referencesignal (CSI-RS) for the second TRP.

Furthermore, the controller 2130 may control to transmit at least one ofconnection grant information, timing advance (TA) information or randomaccess channel (RACH) request information from the TRP2 to the UE usingthe TRP1.

An operation of the controller 2130 is not limited thereto. In anembodiment of the disclosure, the controller 2130 may control theoperations of the base station described through the embodiments ofFIGS. 1 to 19 of the disclosure.

Furthermore, the embodiments disclosed in the specification and drawingshave proposed only specific examples in order to easily describe thecontents of the disclosure and help understanding of the disclosure, andare not intended to restrict the scope of the disclosure. Accordingly,the scope of the disclosure should be construed as including all thechanges or modified forms derived based on the technical spirit of thedisclosure in addition to the disclosed embodiments.

1. An operation method of a terminal, comprising: receiving resourceconfiguration information, comprising reference signal configurationinformation of a first transmission and reception point (TRP) andreference signal configuration information of a second TRP, from thefirst TRP; measuring a reference signal corresponding to the first TRPand a reference signal corresponding to the second TRP based on theresource configuration information; reporting the measurementinformation on the reference signal corresponding to the first TRP andthe reference signal corresponding to the second TRP to the first TRP;receiving TRP change indication information from the first TRP; andchanging a configuration for the second TRP based on the TRP changeindication information.
 2. The method of claim 1, wherein the TRP changeindication information is included in a medium access control (MAC)control element (CE) message.
 3. The method of claim 1, wherein the TRPchange indication information includes a channel stateinformation-reference signal (CSI-RS) for the second TRP.
 4. The methodof claim 1, further comprising receiving at least one of connectiongrant information, timing advance (TA) information or random accesschannel (RACH) request information from the TRP2.
 5. A terminal,comprising: a transceiver configured to transmit and receive signals;and a controller configured to control to receive resource configurationinformation, comprising reference signal configuration information of afirst transmission and reception point (TRP) and reference signalconfiguration information of a second TRP, from the first TRP, tomeasure a reference signal corresponding to the first TRP and areference signal corresponding to the second TRP based on the resourceconfiguration information, report the measurement information on thereference signal corresponding to the first TRP and the reference signalcorresponding to the second TRP to the first TRP, to receive TRP changeindication information from the first TRP, and to change a configurationfor the second TRP based on the TRP change indication information. 6.The terminal of claim 5, wherein the TRP change indication informationis included in a medium access control (MAC) control element (CE)message.
 7. The terminal of claim 5, wherein the TRP change indicationinformation includes a channel state information-reference signal(CSI-RS) for the second TRP.
 8. The terminal of claim 1, wherein thecontroller is configured to control to receive at least one ofconnection grant information, timing advance (TA) information or randomaccess channel (RACH) request information from the TRP2.
 9. An operationmethod of a base station, comprising: transmitting resourceconfiguration information, comprising reference signal configurationinformation of a first transmission and reception point (TRP) andreference signal configuration information of a second TRP, to aterminal through the first TRP; transmitting a reference signalcorresponding to the first TRP and a reference signal corresponding tothe second TRP based on the resource configuration information;receiving measurement information on the reference signal correspondingto the first TRP and the reference signal corresponding to the secondTRP from the terminal; determining a TRP change for the terminal basedon the measurement information; transmitting TRP change indicationinformation to the terminal through the first TRP; and changing aconfiguration of the second TRP for the terminal in accordance with theTRP change indication information.
 10. The operation method of claim 9,wherein the TRP change indication information is included in a mediumaccess control (MAC) control element (CE) message.
 11. The operationmethod of claim 9, wherein the TRP change indication informationincludes a channel state information-reference signal (CSI-RS) for thesecond TRP.
 12. The operation method of claim 9, further comprisingtransmitting at least one of connection grant information, timingadvance (TA) information or random access channel (RACH) requestinformation from the TRP2.
 13. A base station, comprising: a transceiverconfigured to comprise a first transmission and reception point (TRP)and a second TRP; and a controller configured to control to transmitresource configuration information, comprising reference signalconfiguration information of the first TRP and reference signalconfiguration information of the second TRP, to a terminal through thefirst TRP, to transmit a reference signal corresponding to the first TRPand a reference signal corresponding to the second TRP based on theresource configuration information, to receive measurement informationon the reference signal corresponding to the first TRP and the referencesignal corresponding to the second TRP from the terminal, to determine aTRP change for the terminal based on the measurement information, totransmit TRP change indication information to the terminal through thefirst TRP, and to change a configuration of the second TRP for theterminal in accordance with the TRP change indication information. 14.The base station of claim 13, wherein the TRP change indicationinformation is included in a medium access control (MAC) control element(CE) message.
 15. The base station of claim 13, wherein the TRP changeindication information includes a channel state information-referencesignal (CSI-RS) for the second TRP.
 16. The base station of claim 13,wherein the controller is configured to control to transmit at least oneof connection grant information, timing advance (TA) information orrandom access channel (RACH) request information from the TRP2.